Put DirectWrite bitmap fix behind the SK_IGNORE_DWRITE_BITMAP_FIX flag.

src/ports/SkFontHost_win_dw.cpp

Index: src/ports/SkFontHost_win_dw.cpp
===================================================================
--- src/ports/SkFontHost_win_dw.cpp	(revision 14915)
+++ src/ports/SkFontHost_win_dw.cpp	(working copy)
@@ -741,11 +741,24 @@
     // If the scale is negative, this means the matrix will do the flip anyway.
     SkScalar realTextSize = SkScalarAbs(GA.get(SkMatrix::kMScaleY));
     // Due to floating point math, the lower bits are suspect. Round carefully.
+#ifdef SK_IGNORE_DWRITE_BITMAP_FIX
+    SkScalar roundedTextSize = SkScalarRoundToScalar(realTextSize * 64.0f) / 64.0f;
+    SkScalar gdiTextSize = SkScalarFloorToScalar(roundedTextSize);
+#else
     SkScalar gdiTextSize = SkScalarRoundToScalar(realTextSize * 64.0f) / 64.0f;
+#endif
     if (gdiTextSize == 0) {
         gdiTextSize = SK_Scalar1;
     }
 
+#ifdef SK_IGNORE_DWRITE_BITMAP_FIX
+    bool hasBitmap = fRec.fFlags & SkScalerContext::kEmbeddedBitmapText_Flag &&
+                     hasBitmapStrike(typeface, SkScalarTruncToInt(gdiTextSize));
+    bool axisAligned = isAxisAligned(fRec);
+    bool isBiLevel = SkMask::kBW_Format == fRec.fMaskFormat || (hasBitmap && axisAligned);
+
+    if (isBiLevel) {
+#else
     bool bitmapRequested = SkToBool(fRec.fFlags & SkScalerContext::kEmbeddedBitmapText_Flag);
     bool hasBitmap = false;
     bool axisAlignedBitmap = false;
@@ -756,12 +769,13 @@
 
     // If the user requested aliased, do so with aliased compatible metrics.
     if (SkMask::kBW_Format == fRec.fMaskFormat) {
+#endif
         fTextSizeRender = gdiTextSize;
         fRenderingMode = DWRITE_RENDERING_MODE_ALIASED;
         fTextureType = DWRITE_TEXTURE_ALIASED_1x1;
         fTextSizeMeasure = gdiTextSize;
         fMeasuringMode = DWRITE_MEASURING_MODE_GDI_CLASSIC;
-
+#ifndef SK_IGNORE_DWRITE_BITMAP_FIX
     // If we can use a bitmap, use gdi classic rendering and measurement.
     // This will not always provide a bitmap, but matches expected behavior.
     } else if (hasBitmap && axisAlignedBitmap) {
@@ -770,7 +784,7 @@
         fTextureType = DWRITE_TEXTURE_CLEARTYPE_3x1;
         fTextSizeMeasure = gdiTextSize;
         fMeasuringMode = DWRITE_MEASURING_MODE_GDI_CLASSIC;
-
+#endif
     // If rotated but the horizontal text could have used a bitmap,
     // render high quality rotated glyphs but measure using bitmap metrics.
     } else if (hasBitmap) {