Bug 705663 - Fix braindead WebGLTexture::HasImageInfoAt - r=jrmuizel

content/canvas/src/WebGLContext.h

@@ -1087,9 +1087,10 @@ public:
     }
 
     bool HasImageInfoAt(size_t level, size_t face) const {
-        return level <= mMaxLevelWithCustomImages &&
+        CheckedUint32 checked_index = CheckedUint32(level) * mFacesCount + face;
-               face < mFacesCount &&
+        return checked_index.valid() &&
-               ImageInfoAt(level, 0).mIsDefined;
+               checked_index.value() < mImageInfos.Length() &&
+               ImageInfoAt(level, face).mIsDefined;
     }
 
     static size_t FaceForTarget(WebGLenum target) {