diff --git a/dom/canvas/test/webgl-mochitest.ini b/dom/canvas/test/webgl-mochitest.ini
index d6cd17dd6b4e..2fe2009587ca 100644
--- a/dom/canvas/test/webgl-mochitest.ini
+++ b/dom/canvas/test/webgl-mochitest.ini
@@ -3,10 +3,51 @@ subsuite = webgl
 skip-if = ((os == 'linux') && (buildapp == 'b2g'))
 
 support-files =
+  webgl-mochitest/ensure-exts/ensure-ext.js
   webgl-mochitest/driver-info.js
   webgl-mochitest/es3-data.js
   webgl-mochitest/webgl-util.js
 
+[webgl-mochitest/ensure-exts/test_ANGLE_instanced_arrays.html]
+fail-if = (os == 'android') || (os == 'mac')
+[webgl-mochitest/ensure-exts/test_EXT_blend_minmax.html]
+fail-if = (os == 'android')
+[webgl-mochitest/ensure-exts/test_EXT_color_buffer_half_float.html]
+fail-if = (os == 'android')
+[webgl-mochitest/ensure-exts/test_EXT_disjoint_timer_query.html]
+fail-if = (os == 'android') || (os == 'linux') || (os == 'mac') || (os == 'win')
+[webgl-mochitest/ensure-exts/test_EXT_frag_depth.html]
+fail-if = (os == 'android')
+[webgl-mochitest/ensure-exts/test_EXT_sRGB.html]
+fail-if = (os == 'android') || (os == 'linux') || (os == 'mac') || (os == 'win')
+[webgl-mochitest/ensure-exts/test_EXT_shader_texture_lod.html]
+fail-if = (os == 'android') || (os == 'linux') || (os == 'mac')
+[webgl-mochitest/ensure-exts/test_EXT_texture_filter_anisotropic.html]
+fail-if = (os == 'android') || (os == 'linux')
+[webgl-mochitest/ensure-exts/test_OES_standard_derivatives.html]
+fail-if = (os == 'android')
+[webgl-mochitest/ensure-exts/test_WEBGL_color_buffer_float.html]
+fail-if = (os == 'android')
+[webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_atc.html]
+fail-if = (os == 'android') || (os == 'linux') || (os == 'mac') || (os == 'win')
+[webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_es3.html]
+fail-if = (os == 'android') || (os == 'linux') || (os == 'mac') || (os == 'win')
+[webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_etc1.html]
+# Win7 is 6.1
+fail-if = (os == 'linux') || (os == 'mac') || (os == 'win' && os_version == '6.1')
+[webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_pvrtc.html]
+fail-if = (os == 'android') || (os == 'linux') || (os == 'mac') || (os == 'win')
+[webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_s3tc.html]
+fail-if = (os == 'android') || (os == 'linux')
+[webgl-mochitest/ensure-exts/test_WEBGL_depth_texture.html]
+fail-if = (os == 'mac')
+[webgl-mochitest/ensure-exts/test_WEBGL_draw_buffers.html]
+# Win7 is 6.1
+fail-if = (os == 'android') || (os == 'win' && os_version == '6.1')
+
+[webgl-mochitest/ensure-exts/test_common.html]
+
+
 [webgl-mochitest/test_backbuffer_channels.html]
 fail-if = (os == 'b2g')
 [webgl-mochitest/test_depth_readpixels.html]
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/ensure-ext.js b/dom/canvas/test/webgl-mochitest/ensure-exts/ensure-ext.js
new file mode 100644
index 000000000000..798067d5e423
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/ensure-ext.js
@@ -0,0 +1,32 @@
+'use strict';
+
+function EnsureExt(name, shouldBe = true) {
+    var c = document.createElement('canvas');
+    var gl = c.getContext('experimental-webgl');
+
+    if (shouldBe) {
+        ok(gl.getExtension(name), 'Should have extension ' + name + '.');
+    } else {
+        ok(!gl.getExtension(name), 'Should not have extension ' + name + '.');
+    }
+}
+
+function EnsureDraftExt(name, shouldBe = true) {
+    SimpleTest.waitForExplicitFinish();
+
+    var fnEnsure = function() {
+        EnsureExt(name, shouldBe);
+        SimpleTest.finish();
+    };
+
+    if ('SpecialPowers' in window) {
+        var prefStateList = [
+            ['webgl.enable-draft-extensions', true],
+        ];
+        var prefEnv = {'set': prefStateList};
+        SpecialPowers.pushPrefEnv(prefEnv, fnEnsure);
+    } else {
+        console.log('Couldn\'t use SpecialPowers to enable draft extensions.');
+        fnEnsure();
+    }
+}
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_ANGLE_instanced_arrays.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_ANGLE_instanced_arrays.html
new file mode 100644
index 000000000000..04b24d90c109
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_ANGLE_instanced_arrays.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('ANGLE_instanced_arrays');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_blend_minmax.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_blend_minmax.html
new file mode 100644
index 000000000000..903269e6b663
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_blend_minmax.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('EXT_blend_minmax');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_color_buffer_half_float.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_color_buffer_half_float.html
new file mode 100644
index 000000000000..3ac21299c686
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_color_buffer_half_float.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('EXT_color_buffer_half_float');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_disjoint_timer_query.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_disjoint_timer_query.html
new file mode 100644
index 000000000000..e0b90adbbb5b
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_disjoint_timer_query.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureDraftExt('EXT_disjoint_timer_query');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_frag_depth.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_frag_depth.html
new file mode 100644
index 000000000000..3c7f38679178
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_frag_depth.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('EXT_frag_depth');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_sRGB.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_sRGB.html
new file mode 100644
index 000000000000..da5aa0a3fbfb
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_sRGB.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('EXT_sRGB');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_shader_texture_lod.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_shader_texture_lod.html
new file mode 100644
index 000000000000..e64ff94848c5
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_shader_texture_lod.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('EXT_shader_texture_lod');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_texture_filter_anisotropic.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_texture_filter_anisotropic.html
new file mode 100644
index 000000000000..877c4440bf30
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_EXT_texture_filter_anisotropic.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('EXT_texture_filter_anisotropic');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_OES_standard_derivatives.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_OES_standard_derivatives.html
new file mode 100644
index 000000000000..3e7b7a396226
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_OES_standard_derivatives.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('OES_standard_derivatives');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_color_buffer_float.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_color_buffer_float.html
new file mode 100644
index 000000000000..aeb8f271ea05
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_color_buffer_float.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_color_buffer_float');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_atc.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_atc.html
new file mode 100644
index 000000000000..6d68f0b4e2b2
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_atc.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_compressed_texture_atc');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_es3.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_es3.html
new file mode 100644
index 000000000000..21c824ad8546
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_es3.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureDraftExt('WEBGL_compressed_texture_es3');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_etc1.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_etc1.html
new file mode 100644
index 000000000000..327625c01848
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_etc1.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_compressed_texture_etc1');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_pvrtc.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_pvrtc.html
new file mode 100644
index 000000000000..c95481398421
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_pvrtc.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_compressed_texture_pvrtc');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_s3tc.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_s3tc.html
new file mode 100644
index 000000000000..6ad800110648
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_compressed_texture_s3tc.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_compressed_texture_s3tc');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_depth_texture.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_depth_texture.html
new file mode 100644
index 000000000000..957171c160e3
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_depth_texture.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_depth_texture');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_draw_buffers.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_draw_buffers.html
new file mode 100644
index 000000000000..18774d0d68a0
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_WEBGL_draw_buffers.html
@@ -0,0 +1,17 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+    <script src='ensure-ext.js'></script>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+EnsureExt('WEBGL_draw_buffers');
+
+    </script>
+  </body>
+</html>
diff --git a/dom/canvas/test/webgl-mochitest/ensure-exts/test_common.html b/dom/canvas/test/webgl-mochitest/ensure-exts/test_common.html
new file mode 100644
index 000000000000..3b5907a8a886
--- /dev/null
+++ b/dom/canvas/test/webgl-mochitest/ensure-exts/test_common.html
@@ -0,0 +1,75 @@
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <meta charset='utf-8'/>
+    <script src='/tests/SimpleTest/SimpleTest.js'></script>
+    <link rel='stylesheet' href='/tests/SimpleTest/test.css'>
+  </head>
+  <body>
+    <script>
+
+'use strict';
+
+var c = document.createElement('canvas');
+var gl = c.getContext('experimental-webgl');
+
+function ensureExt(name) {
+  ok(gl.getExtension(name), 'Should have extension ' + name + '.');
+}
+
+function ensureNoExt(name) {
+  ok(!gl.getExtension(name), 'Should not have extension ' + name + '.');
+}
+
+do {
+  if (!gl)
+    break;
+
+  // These aren't all guaranteed, but they're common to all our test slaves.
+  // If you're adding a slave config that is missing one of these, comment the line out
+  // and split it into its own test.
+
+  // Implemented. (commented out if not test-slave-universal)
+  //ensureExt('ANGLE_instanced_arrays');
+  //ensureExt('EXT_blend_minmax');
+  //ensureExt('EXT_color_buffer_half_float');
+  //ensureExt('EXT_frag_depth');
+  //ensureExt('EXT_shader_texture_lod');
+  //ensureExt('EXT_sRGB');
+  //ensureExt('EXT_texture_filter_anisotropic');
+  ensureExt('OES_element_index_uint');
+  //ensureExt('OES_standard_derivatives');
+  ensureExt('OES_texture_float');
+  ensureExt('OES_texture_float_linear');
+  ensureExt('OES_texture_half_float');
+  ensureExt('OES_texture_half_float_linear');
+  ensureExt('OES_vertex_array_object');
+  //ensureExt('WEBGL_color_buffer_float');
+  //ensureExt('WEBGL_compressed_texture_atc');
+  //ensureExt('WEBGL_compressed_texture_es3');
+  //ensureExt('WEBGL_compressed_texture_etc1');
+  //ensureExt('WEBGL_compressed_texture_pvrtc');
+  //ensureExt('WEBGL_compressed_texture_s3tc');
+  //ensureExt('WEBGL_depth_texture');
+  //ensureExt('WEBGL_draw_buffers');
+  ensureExt('WEBGL_lose_context');
+
+  // Draft extensions, which should not be exposed by default.
+  ensureNoExt('EXT_disjoint_timer_query');
+  ensureNoExt('WEBGL_compressed_texture_es3');
+
+  // Not implemented.
+  ensureNoExt('EXT_color_buffer_float');
+  ensureNoExt('OES_fbo_render_mipmap');
+  ensureNoExt('WEBGL_compressed_texture_astc');
+  ensureNoExt('WEBGL_security_sensitive_resources');
+  ensureNoExt('WEBGL_shared_resources');
+
+  // Privileged
+  //ensureExt('WEBGL_debug_renderer_info');
+  //ensureExt('WEBGL_debug_shaders');
+} while (false);
+
+    </script>
+  </body>
+</html>