Bug 1309643 - Only enable primitive restart index on OSX for DrawElements. - r=ethlin

dom/canvas/WebGL2Context.cpp

@@ -175,7 +175,6 @@ WebGLContext::InitWebGL2(FailureReason* const out_failReason)
         gl->fEnable(LOCAL_GL_PRIMITIVE_RESTART_FIXED_INDEX);
     } else {
         MOZ_ASSERT(gl->IsSupported(gl::GLFeature::prim_restart));
-        gl->fEnable(LOCAL_GL_PRIMITIVE_RESTART);
     }
 
     //////

dom/canvas/WebGLContextDraw.cpp

@@ -270,11 +270,11 @@ WebGLContext::DrawArrays_check(const char* funcName, GLenum mode, GLint first,
 
     if (IsWebGL2() && !gl->IsSupported(gl::GLFeature::prim_restart_fixed)) {
         MOZ_ASSERT(gl->IsSupported(gl::GLFeature::prim_restart));
-        if (mPrimRestartTypeBytes != 4) {
-            mPrimRestartTypeBytes = 4;
+        if (mPrimRestartTypeBytes != 0) {
+            mPrimRestartTypeBytes = 0;
 
-            // OSX has issues leaving this as 0.
-            gl->fPrimitiveRestartIndex(UINT32_MAX);
+            // OSX appears to have severe perf issues with leaving this enabled.
+            gl->fDisable(LOCAL_GL_PRIMITIVE_RESTART);
         }
     }
 
@@ -630,6 +630,7 @@ WebGLContext::DrawElements_check(const char* funcName, GLenum mode, GLsizei vert
             mPrimRestartTypeBytes = bytesPerElem;
 
             const uint32_t ones = UINT32_MAX >> (4 - mPrimRestartTypeBytes);
+            gl->fEnable(LOCAL_GL_PRIMITIVE_RESTART);
             gl->fPrimitiveRestartIndex(ones);
         }
     }

gfx/gl/GLContextFeatures.cpp

@@ -445,7 +445,7 @@ static const FeatureInfo sFeatureInfoArr[] = {
         GLESVersion::NONE,
         GLContext::Extension_None,
         {
-            GLContext::NV_primitive_restart,
+            //GLContext::NV_primitive_restart, // Has different enum values.
             GLContext::Extensions_End
         }
     },