Fix error handling in DirectWrite with tiny text.

src/ports/SkScalerContext_win_dw.h

Index: src/ports/SkScalerContext_win_dw.h
diff --git a/src/ports/SkScalerContext_win_dw.h b/src/ports/SkScalerContext_win_dw.h
index e9eab94de12435bc3d77f3a84a7a3b974aec15d7..0bd79e7d82639cbbed3774bc4692c01a5f034b68 100644
--- a/src/ports/SkScalerContext_win_dw.h
+++ b/src/ports/SkScalerContext_win_dw.h
@@ -37,10 +37,10 @@ private:
                            DWRITE_RENDERING_MODE renderingMode,
                            DWRITE_TEXTURE_TYPE textureType);
 
-    void getBoundingBox(SkGlyph* glyph,
-                        DWRITE_RENDERING_MODE renderingMode,
-                        DWRITE_TEXTURE_TYPE textureType,
-                        RECT* bbox);
+    HRESULT getBoundingBox(SkGlyph* glyph,
+                           DWRITE_RENDERING_MODE renderingMode,
+                           DWRITE_TEXTURE_TYPE textureType,
+                           RECT* bbox);
 
     SkTDArray<uint8_t> fBits;
     /** The total matrix without the text height scale. */