Fix crash in canvas.toBlob caused by allocation failure

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index 1113e5d4ab6c4b70651e21ca82343c625e1d59b7..4a111e61cb7b2e8f66d5ad11de00a65a803ad417 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -4264,7 +4264,7 @@ void WebGLRenderingContextBase::texImageCanvasByGPU(HTMLCanvasElement* canvas, G
 {
     if (!canvas->is3D()) {
         ImageBuffer* buffer = canvas->buffer();
-        if (!buffer->copyToPlatformTexture(contextGL(), targetTexture, targetInternalformat, targetType,
+        if (buffer && !buffer->copyToPlatformTexture(contextGL(), targetTexture, targetInternalformat, targetType,
             targetLevel, m_unpackPremultiplyAlpha, m_unpackFlipY)) {
             NOTREACHED();
         }