Remove A8_LCD luminance hack.

It no longer appears to be necessary, and the powf function is slowing down
Android text rendering.

R=bungeman@google.com, bsalomon@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/337603008

expectations/gm/ignored-tests.txt

@@ -51,3 +51,97 @@ bigblurs
 perlinnoise
 perlinnoise_localmatrix
 imagefiltersscaled
+
+# jvanverth:
+# A8 text gamma changes slightly
+# https://codereview.chromium.org/348153002/
+imageblurtiled
+filterbitmap_text_3.00pt
+filterbitmap_text_7.00pt
+filterbitmap_text_10.00pt
+texteffects
+gammatext
+fontscaler
+imageblur_large
+imageblur
+convex_poly_clip
+fontcache
+varied_text_ignorable_clip_lcd
+imageresizetiled
+fontmgr_iter
+varied_text_clipped_no_lcd
+typefacestyles_kerning
+downsamplebitmap_text_high_72.00pt
+downsamplebitmap_text_medium_72.00pt
+degeneratesegments
+verttext2
+varied_text_clipped_lcd
+cubicclosepath
+quadclosepath
+lineclosepath
+cubicpath
+quadpath
+linepath
+imagefiltersgraph
+gradtext
+drawlooper
+emptypath
+lcdtext
+matrixconvolution
+typefacestyles
+morphology
+downsamplebitmap_text_low_72.00pt
+fontmgr_match
+lighting
+imagemagnifier
+xfermodes2
+downsamplebitmap_text_none_72.00pt
+displacement
+xfermodes
+shadertext
+arithmode
+verttext
+bitmapsource
+xfermodes3
+typeface
+twopointconical
+stroketext
+complexclip_aa
+complexclip_bw
+stroke-fill
+tileimagefilter
+getpostextpath
+drawbitmaprect
+simpleaaclip_aaclip
+simpleaaclip_path
+simpleaaclip_rect
+shadertext2
+blurs
+complexclip_aa_layer
+complexclip_bw_layer
+scaled_tilemodes_npot
+tilemodes
+tilemodes_npot
+scaled_tilemodes
+bitmapfilters
+imagefiltersbase
+pictureimagefilter
+srcmode
+image-surface
+scaled_tilemode_bitmap
+scaled_tilemode_gradient
+tilemode_bitmap
+tilemode_gradient
+xfermodeimagefilter
+dropshadowimagefilter
+internal_links
+offsetimagefilter
+bitmapcopy
+samplerstress
+imagefilterscropped
+poly2poly
+# senorblanco: 
+# Needs rebaselining after improved perlin noise scaling
+perlinnoise
+perlinnoise_localmatrix
+imagefiltersscaled

src/core/SkPaint.cpp

@@ -1778,15 +1778,19 @@ void SkScalerContext::PostMakeRec(const SkPaint&, SkScalerContext::Rec* rec) {
         case SkMask::kA8_Format: {
             // filter down the luminance to a single component, since A8 can't
             // use per-component information
-
             SkColor color = rec->getLuminanceColor();
+#ifdef SK_IGNORE_FASTER_TEXT_FIX
             U8CPU lum = SkColorSpaceLuminance::computeLuminance(rec->getPaintGamma(), color);
             //If we are asked to look like LCD, look like LCD.
             if (!(rec->fFlags & SkScalerContext::kGenA8FromLCD_Flag)) {
                 // HACK: Prevents green from being pre-blended as white.
                 lum -= ((255 - lum) * lum) / 255;
             }
-
+#else
+            U8CPU lum = SkComputeLuminance(SkColorGetR(color),
+                                           SkColorGetG(color),
+                                           SkColorGetB(color));
+#endif
             // reduce to our finite number of bits
             color = SkColorSetRGB(lum, lum, lum);
             rec->setLuminanceColor(SkMaskGamma::CanonicalColor(color));