Introduce Props to surface (patchset #27 id:520001 of https://codereview.chromium.org/551463004/)"

This reverts commit 29c857d0f3a1cb837f73406eeb6ba9771879b5e7.

TBR=

Author: reed@google.com

Review URL: https://codereview.chromium.org/588143004
diff --git a/src/ports/SkImageDecoder_CG.cpp b/src/ports/SkImageDecoder_CG.cpp
index 5b32502..3e3075c 100644
--- a/src/ports/SkImageDecoder_CG.cpp
+++ b/src/ports/SkImageDecoder_CG.cpp
@@ -40,6 +40,7 @@
 
 static CGImageSourceRef SkStreamToCGImageSource(SkStream* stream) {
     CGDataProviderRef data = SkStreamToDataProvider(stream);
+    SkASSERT(data);
     CGImageSourceRef imageSrc = CGImageSourceCreateWithDataProvider(data, 0);
     CGDataProviderRelease(data);
     return imageSrc;