Revert of De-flaking some tests in virtual/gpu/fast/canvas

LayoutTests/fast/canvas/resources/asyncpaintguard.js

Index: LayoutTests/fast/canvas/resources/asyncpaintguard.js
diff --git a/LayoutTests/fast/canvas/resources/asyncpaintguard.js b/LayoutTests/fast/canvas/resources/asyncpaintguard.js
deleted file mode 100644
index dea5671973a61ada24286d4f2f1760a6052a2a15..0000000000000000000000000000000000000000
--- a/LayoutTests/fast/canvas/resources/asyncpaintguard.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// In tests that are not explicitly async, include this file to ensure
-// paint completion before the layout test pixel results are captured.
-
-if (window.testRunner)
-    testRunner.waitUntilDone();
-
-function finishTest() {
-    if (window.testRunner) {
-        testRunner.layoutAndPaintAsyncThen(function () { testRunner.notifyDone(); });
-    }
-}
-
-window.addEventListener("load", finishTest, false);