From d2ad89c8f40b127e18bb8d6b888596e286740500 Mon Sep 17 00:00:00 2001
From: Guillaume Abadie <guillaume.abadie@gmail.com>
Date: Thu, 29 Aug 2013 10:14:22 -0400
Subject: [PATCH] Bug 645792 - Replace throwing an exception by returning null
 on HTMLCanvasElement::GetContext. r=bjacob CLOSED TREE

---
 .../test/crossorigin/test_webgl_crossorigin_textures.html    | 5 ++---
 content/html/content/src/HTMLCanvasElement.cpp               | 1 +
 dom/bindings/test/test_integers.html                         | 5 ++---
 dom/bindings/test/test_sequence_wrapping.html                | 5 ++---
 4 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/content/canvas/test/crossorigin/test_webgl_crossorigin_textures.html b/content/canvas/test/crossorigin/test_webgl_crossorigin_textures.html
index 29a5edee5a31..2ca9a342427b 100644
--- a/content/canvas/test/crossorigin/test_webgl_crossorigin_textures.html
+++ b/content/canvas/test/crossorigin/test_webgl_crossorigin_textures.html
@@ -66,9 +66,8 @@
 
   MochiKit.DOM.addLoadEvent(function () {
     var canvas = document.getElementById("canvas");
-    try {
-      gl = canvas.getContext("experimental-webgl");
-    } catch (e) {
+    gl = canvas.getContext("experimental-webgl");
+    if (!gl) {
       todo(false, "Canvas WebGL not supported");
       SimpleTest.finish();
       return;
diff --git a/content/html/content/src/HTMLCanvasElement.cpp b/content/html/content/src/HTMLCanvasElement.cpp
index 6b57910efdc3..21eee4079c87 100644
--- a/content/html/content/src/HTMLCanvasElement.cpp
+++ b/content/html/content/src/HTMLCanvasElement.cpp
@@ -804,6 +804,7 @@ HTMLCanvasElement::GetContext(JSContext* aCx,
 
     rv = UpdateContext(aCx, aContextOptions);
     if (rv.Failed()) {
+      rv = NS_OK; // See bug 645792
       return nullptr;
     }
     mCurrentContextId.Assign(aContextId);
diff --git a/dom/bindings/test/test_integers.html b/dom/bindings/test/test_integers.html
index 0b1cdacea2fb..c74b68216c84 100644
--- a/dom/bindings/test/test_integers.html
+++ b/dom/bindings/test/test_integers.html
@@ -16,9 +16,8 @@
   function testInt64NonFinite(arg) {
     // We can use a WebGLRenderingContext to test conversion to 64-bit signed
     // ints edge cases.
-    try {
-      var gl = $("c").getContext("experimental-webgl");
-    } catch (ex) {
+    var gl = $("c").getContext("experimental-webgl");
+    if (!gl) {
       // No WebGL support on MacOS 10.5.  Just skip this test
       todo(false, "WebGL not supported");
       return;
diff --git a/dom/bindings/test/test_sequence_wrapping.html b/dom/bindings/test/test_sequence_wrapping.html
index e4f18f9986c3..7132e56019d7 100644
--- a/dom/bindings/test/test_sequence_wrapping.html
+++ b/dom/bindings/test/test_sequence_wrapping.html
@@ -20,9 +20,8 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=775852
 
 /** Test for Bug 775852 **/
 function doTest() {
-  try {
-    var gl = $("c").getContext("experimental-webgl");
-  } catch (e) {
+  var gl = $("c").getContext("experimental-webgl");
+  if (!gl) {
     // No WebGL support on MacOS 10.5.  Just skip this test
     todo(false, "WebGL not supported");
     return;