Add premultiplyAlpha to ImageBitmap support check
Add premultiplyAlpha to ImageBitmap support check

progsung/cesium,likangning93/cesium,jasonbeverage/cesium,josh-bernstein/cesium,CesiumGS/cesium,YonatanKra/cesium,progsung/cesium,jasonbeverage/cesium,geoscan/cesium,YonatanKra/cesium,CesiumGS/cesium,CesiumGS/cesium,likangning93/cesium,YonatanKra/cesium,likangning93/cesium,CesiumGS/cesium,AnalyticalGraphicsInc/cesium,likangning93/cesium,AnalyticalGraphicsInc/cesium,geoscan/cesium,josh-bernstein/cesium,likangning93/cesium,CesiumGS/cesium,YonatanKra/cesium