Revert of Add the method isOpaque() to SkImage

src/image/SkImage_Codec.cpp

Index: src/image/SkImage_Codec.cpp
diff --git a/src/image/SkImage_Codec.cpp b/src/image/SkImage_Codec.cpp
index 0b14216a064d9c6d81670f418b25692b58a9c8bf..21c844d01dd331b0f4235f215fc11ad494fb84bf 100644
--- a/src/image/SkImage_Codec.cpp
+++ b/src/image/SkImage_Codec.cpp
@@ -21,8 +21,6 @@
     virtual void onDraw(SkCanvas*, SkScalar, SkScalar, const SkPaint*) const SK_OVERRIDE;
     virtual void onDrawRectToRect(SkCanvas*, const SkRect*, const SkRect&,
                                   const SkPaint*) const SK_OVERRIDE;
-
-    virtual bool isOpaque() const SK_OVERRIDE;
 
 private:
     SkData*     fEncodedData;
@@ -80,8 +78,3 @@
 
     return SkNEW_ARGS(SkImage_Codec, (data, bitmap.width(), bitmap.height()));
 }
-
-
-bool SkImage_Codec::isOpaque() const {
-    return fBitmap.isOpaque();
-}