diff -r 000000000000 -r 6474c204b198 browser/devtools/shadereditor/test/browser_webgl-actor-test-13.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/shadereditor/test/browser_webgl-actor-test-13.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,67 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests if multiple WebGL contexts are correctly handled.
+ */
+
+function ifWebGLSupported() {
+  let [target, debuggee, front] = yield initBackend(MULTIPLE_CONTEXTS_URL);
+  front.setup({ reload: true });
+
+  let [firstProgramActor, secondProgramActor] = yield getPrograms(front, 2);
+
+  isnot(firstProgramActor, secondProgramActor,
+    "Two distinct program actors were recevide from two separate contexts.");
+
+  let firstVertexShader = yield firstProgramActor.getVertexShader();
+  let firstFragmentShader = yield firstProgramActor.getFragmentShader();
+  let secondVertexShader = yield secondProgramActor.getVertexShader();
+  let secondFragmentShader = yield secondProgramActor.getFragmentShader();
+
+  isnot(firstVertexShader, secondVertexShader,
+    "The two programs should have distinct vertex shaders.");
+  isnot(firstFragmentShader, secondFragmentShader,
+    "The two programs should have distinct fragment shaders.");
+
+  let firstVertSource = yield firstVertexShader.getText();
+  let firstFragSource = yield firstFragmentShader.getText();
+  let secondVertSource = yield secondVertexShader.getText();
+  let secondFragSource = yield secondFragmentShader.getText();
+
+  is(firstVertSource, secondVertSource,
+    "The vertex shaders should have identical sources.");
+  is(firstFragSource, secondFragSource,
+    "The vertex shaders should have identical sources.");
+
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  ok(true, "The two canvases are correctly drawn.");
+
+  yield firstProgramActor.highlight([1, 0, 0, 1]);
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  ok(true, "The first canvas was correctly filled after highlighting.");
+
+  yield secondProgramActor.highlight([0, 1, 0, 1]);
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+  ok(true, "The second canvas was correctly filled after highlighting.");
+
+  yield firstProgramActor.unhighlight();
+  yield secondProgramActor.unhighlight();
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(debuggee, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  ok(true, "The two canvases were correctly filled after unhighlighting.");
+
+  yield removeTab(target.tab);
+  finish();
+}