Fixing Canvas2DLayerBridge to handle lost graphics contexts

LayoutTests/fast/canvas/canvas-lost-gpu-context-expected.txt

Index: LayoutTests/fast/canvas/canvas-lost-gpu-context-expected.txt
diff --git a/LayoutTests/fast/canvas/canvas-lost-gpu-context-expected.txt b/LayoutTests/fast/canvas/canvas-lost-gpu-context-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..ff638c9b382b4db04081f183b2747cee8764c744
--- /dev/null
+++ b/LayoutTests/fast/canvas/canvas-lost-gpu-context-expected.txt
@@ -0,0 +1,14 @@
+Test the behavior of canvas recovery after a gpu context loss
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS imgdata[0] is 255
+PASS imgdata[1] is 0
+PASS imgdata[2] is 0
+PASS imgdata[3] is 255
+Aborting test: Graphics context loss did not destroy canvas contents. This is expected if canvas is not accelerated.
+PASS successfullyParsed is true
+
+TEST COMPLETE
+