Fix undefined behavior in DirectWrite GDI compatible metrics.

src/ports/SkFontHost_win_dw.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkTypes.h"
 #undef GetGlyphIndices
 
@@ skipping 783 matching lines @@
     fXform.dy = 0;
 
     // GsA is the non-rotational part of A without the text height scale.
     SkMatrix GsA(GA);
     GsA.preScale(scale, scale); //remove text height scale, G is rotational so reorders with scale.
 
     fGsA.m11 = SkScalarToFloat(GsA.get(SkMatrix::kMScaleX));
     fGsA.m12 = SkScalarToFloat(GsA.get(SkMatrix::kMSkewY)); // This should be ~0.
     fGsA.m21 = SkScalarToFloat(GsA.get(SkMatrix::kMSkewX));
     fGsA.m22 = SkScalarToFloat(GsA.get(SkMatrix::kMScaleY));
+    fGsA.dx = 0;
+    fGsA.dy = 0;
 
     // fG_inv is G inverse, which is fairly simple since G is 2x2 rotational.
     fG_inv.setAll(G.get(SkMatrix::kMScaleX), -G.get(SkMatrix::kMSkewX), G.get(SkMatrix::kMTransX),
                   -G.get(SkMatrix::kMSkewY), G.get(SkMatrix::kMScaleY), G.get(SkMatrix::kMTransY),
                   G.get(SkMatrix::kMPersp0), G.get(SkMatrix::kMPersp1), G.get(SkMatrix::kMPersp2));
 }
 
 SkScalerContext_DW::~SkScalerContext_DW() {
 }
 
@@ skipping 1188 matching lines @@
 }
 
 #include "SkFontMgr_indirect.h"
 SkFontMgr* SkFontMgr_New_DirectWriteRenderer(SkRemotableFontMgr* proxy) {
     SkAutoTUnref<SkFontMgr> impl(SkFontMgr_New_DirectWrite());
     if (impl.get() == NULL) {
         return NULL;
     }
     return SkNEW_ARGS(SkFontMgr_Indirect, (impl.get(), proxy));
 }