Revert "Do not use sub-pixel positioning for source space"

This reverts commit 7b56b0ae39.

Reason for revert: speculative: broke win7 layout tests

Original change's description:
> Do not use sub-pixel positioning for source space
> 
> Since the source space drawing modes call getGlyphMetrics with
> the point {0, 0}, just turn of sub-pixel positioning. This uses
> a more efficient code path in the strike
> 
> Change-Id: I360f56e1eede776dfa82db6b780b88c1fda50d36
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206701
> Reviewed-by: Ben Wagner <bungeman@google.com>
> Commit-Queue: Ben Wagner <bungeman@google.com>
> Commit-Queue: Herb Derby <herb@google.com>
> Auto-Submit: Herb Derby <herb@google.com>

TBR=bungeman@google.com,herb@google.com

Change-Id: I06cafe542fe6374d1a273db09617dbebd9eb04c7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/206696
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>

src/core/SkFont.cpp

@@ -124,9 +124,6 @@ SkScalar SkFont::setupForAsPaths(SkPaint* paint) {
         this->setEdging(Edging::kAntiAlias);
     }
 
-    // The sub-pixel position will always happen when transforming to the screen.
-    this->setSubpixel(false);
-
     if (paint) {
         paint->setStyle(SkPaint::kFill_Style);
         paint->setPathEffect(nullptr);

src/core/SkGlyphRunPainter.cpp

@@ -333,9 +333,6 @@ void SkGlyphRunListPainter::processARGBFallback(SkScalar maxSourceGlyphDimension
         SkFont fallbackFont{runFont};
         fallbackFont.setSize(fallbackTextSize);
 
-        // No sub-pixel needed. The transform to the screen will take care of sub-pixel positioning.
-        fallbackFont.setSubpixel(false);
-
         // The scale factor to go from strike size to the source size for glyphs.
         SkScalar fallbackTextScale = runFontTextSize / fallbackTextSize;
 

src/gpu/text/GrTextContext.cpp

@@ -172,9 +172,7 @@ SkFont GrTextContext::InitDistanceFieldFont(const SkFont& font,
     dfFont.setEdging(SkFont::Edging::kAntiAlias);
     dfFont.setForceAutoHinting(false);
     dfFont.setHinting(kNormal_SkFontHinting);
-
-    // The sub-pixel position will always happen when transforming to the screen.
-    dfFont.setSubpixel(false);
+    dfFont.setSubpixel(true);
     return dfFont;
 }