Mark WebGLRenderingContext as having lost context upon init failure.

Source/core/html/canvas/WebGLRenderingContextBase.cpp

Index: Source/core/html/canvas/WebGLRenderingContextBase.cpp
diff --git a/Source/core/html/canvas/WebGLRenderingContextBase.cpp b/Source/core/html/canvas/WebGLRenderingContextBase.cpp
index 0eb087e0216d3a9ef72e31521ebca34111a3a719..405de6fe6b88d123613b8cc95f5f6f2cab1126d8 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.cpp
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.cpp
@@ -645,8 +645,10 @@ WebGLRenderingContextBase::WebGLRenderingContextBase(HTMLCanvasElement* passedCa
     context->getIntegerv(GL_MAX_VIEWPORT_DIMS, m_maxViewportDims);
 
     RefPtr<DrawingBuffer> buffer = createDrawingBuffer(context);
-    if (!buffer)
+    if (!buffer) {
+        m_contextLostMode = SyntheticLostContext;
         return;
+    }
 
 #if ENABLE(OILPAN)
     m_sharedWebGraphicsContext3D = WebGLSharedWebGraphicsContext3D::create(buffer.release());