Abort ContextLost.WebGLContextLostFromQuantity if context creation fails.

content/test/gpu/gpu_tests/context_lost.py

Index: content/test/gpu/gpu_tests/context_lost.py
diff --git a/content/test/gpu/gpu_tests/context_lost.py b/content/test/gpu/gpu_tests/context_lost.py
index 433248901df3622f92d578c9942b6ac67ae36774..5d0100963fd6b1335915ef3b828df5a78e68f4ae 100644
--- a/content/test/gpu/gpu_tests/context_lost.py
+++ b/content/test/gpu/gpu_tests/context_lost.py
@@ -32,9 +32,13 @@ harness_script = r"""
     if (msg == "loaded") {
       domAutomationController._loaded = true;
     } else if (msg == "success") {
-      domAutomationController._succeeded = true;
+      /* Don't squelch earlier failures! */
+      if (!domAutomationController._finished) {
+        domAutomationController._succeeded = true;
+      }
       domAutomationController._finished = true;
     } else {
+      /* Always record failures. */
       domAutomationController._succeeded = false;
       domAutomationController._finished = true;
     }