MediaRecorder: ASSERT-->DCHECK and a tiny cleanup in CanvasCapture

third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp

Index: third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
diff --git a/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp b/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
index 18550f3294dbcee42236eec3210917a5775bc2d6..17c81e4cd2817c6664d5dcac5d16e0729ea5fe59 100644
--- a/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
+++ b/third_party/WebKit/Source/modules/mediacapturefromelement/HTMLCanvasElementCapture.cpp
@@ -42,13 +42,13 @@ MediaStream* HTMLCanvasElementCapture::captureStream(HTMLCanvasElement& element,
     }
 
     WebMediaStreamTrack track;
-    WebSize size(element.width(), element.height());
+    const WebSize size(element.width(), element.height());
     OwnPtr<WebCanvasCaptureHandler> handler;
     if (givenFrameRate)
         handler = adoptPtr(Platform::current()->createCanvasCaptureHandler(size, frameRate, &track));
     else
         handler = adoptPtr(Platform::current()->createCanvasCaptureHandler(size, kDefaultFrameRate, &track));
-    ASSERT(handler);
+
     if (!handler) {
         exceptionState.throwDOMException(NotSupportedError, "No CanvasCapture handler can be created.");
         return nullptr;