Add the "experimental canvas features" flag, and plumb it through to

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 9076ee9565188d6af5f526d1a6275650b9bbf969..31c2805ddd68ff15515e99f0a288cbdc98ba52ea 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -796,6 +796,9 @@ void RenderThreadImpl::EnsureWebKitInitialized() {
   WebRuntimeFeatures::enableExperimentalWebSocket(
       command_line.HasSwitch(switches::kEnableExperimentalWebSocket));
 
+  WebRuntimeFeatures::enableExperimentalCanvasFeatures(
+      command_line.HasSwitch(switches::kEnableExperimentalCanvasFeatures));
+
   FOR_EACH_OBSERVER(RenderProcessObserver, observers_, WebKitInitialized());
 
   devtools_agent_message_filter_ = new DevToolsAgentFilter();