Merge 185069 "Enforce context refrence guards in WebGL extensions."

Source/core/html/canvas/WebGLLoseContext.cpp

Index: Source/core/html/canvas/WebGLLoseContext.cpp
===================================================================
--- Source/core/html/canvas/WebGLLoseContext.cpp	(revision 187498)
+++ Source/core/html/canvas/WebGLLoseContext.cpp	(working copy)
@@ -58,14 +58,16 @@
 
 void WebGLLoseContext::loseContext()
 {
-    if (!isLost())
-        m_context->forceLostContext(WebGLRenderingContextBase::WebGLLoseContextLostContext, WebGLRenderingContextBase::Manual);
+    WebGLExtensionScopedContext scoped(this);
+    if (!scoped.isLost())
+        scoped.context()->forceLostContext(WebGLRenderingContextBase::WebGLLoseContextLostContext, WebGLRenderingContextBase::Manual);
 }
 
 void WebGLLoseContext::restoreContext()
 {
-    if (!isLost())
-        m_context->forceRestoreContext();
+    WebGLExtensionScopedContext scoped(this);
+    if (!scoped.isLost())
+        scoped.context()->forceRestoreContext();
 }
 
 bool WebGLLoseContext::supported(WebGLRenderingContextBase*)