Oilpan: unbreak WebGL context lost tests following r190259.

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 b6427550f94d9d405c7927f5c87cbd3b588e23c8..322a4f9101af436fd42235e2fd05ccfe5263c0f0 100644
--- a/Source/core/html/canvas/WebGLRenderingContextBase.cpp
+++ b/Source/core/html/canvas/WebGLRenderingContextBase.cpp
@@ -2251,10 +2251,9 @@ bool WebGLRenderingContextBase::extensionSupportedAndAllowed(const ExtensionTrac
     return true;
 }
 
-
 ScriptValue WebGLRenderingContextBase::getExtension(ScriptState* scriptState, const String& name)
 {
-    RefPtrWillBeRawPtr<WebGLExtension> extension;
+    RefPtrWillBeRawPtr<WebGLExtension> extension = nullptr;
 
     if (!isContextLost()) {
         for (size_t i = 0; i < m_extensions.size(); ++i) {