Make WebGL extensions get lost when context is lost.

Source/core/html/canvas/WebGLDebugShaders.cpp

Index: Source/core/html/canvas/WebGLDebugShaders.cpp
diff --git a/Source/core/html/canvas/WebGLDebugShaders.cpp b/Source/core/html/canvas/WebGLDebugShaders.cpp
index 9adcfa15b91286aa7bf25a1825fd0effb2ecb81d..8d1d2a3e3b417423baa9fc78b8a88f2fa1fbc67e 100644
--- a/Source/core/html/canvas/WebGLDebugShaders.cpp
+++ b/Source/core/html/canvas/WebGLDebugShaders.cpp
@@ -39,12 +39,17 @@ WebGLDebugShaders::WebGLDebugShaders(WebGLRenderingContext* context)
     : WebGLExtension(context)
 {
     ScriptWrappable::init(this);
+    enable();
 }
 
 WebGLDebugShaders::~WebGLDebugShaders()
 {
 }
 
+void WebGLDebugShaders::enable()
+{
+}
+
 WebGLExtension::ExtensionName WebGLDebugShaders::getName() const
 {
     return WebGLDebugShadersName;
@@ -58,7 +63,7 @@ PassOwnPtr<WebGLDebugShaders> WebGLDebugShaders::create(WebGLRenderingContext* c
 String WebGLDebugShaders::getTranslatedShaderSource(WebGLShader* shader, ExceptionCode& ec)
 {
     UNUSED_PARAM(ec);
-    if (m_context->isContextLost())
+    if (isLost())
         return String();
     if (!m_context->validateWebGLObject("getTranslatedShaderSource", shader))
         return "";