diff -r 000000000000 -r 6474c204b198 dom/imptests/html/webgl/common.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/imptests/html/webgl/common.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+function getGl() {
+  var c = document.createElement("canvas");
+  var gl = c.getContext("experimental-webgl");
+  assert_true(!!gl, "Should be able to get a context.");
+  return gl;
+}
+
+function shouldGenerateGLError(cx, glError, fn) {
+  test(function() {
+    fn();
+    assert_equals(cx.getError(), glError);
+  }, "Calling " + fn + " should generate a " + glError + " error.");
+}