Revert "Merge FontPlatformDataHarfBuzz into FontPlatformData"

Source/platform/BUILD.gn

Index: Source/platform/BUILD.gn
diff --git a/Source/platform/BUILD.gn b/Source/platform/BUILD.gn
index 154d902e87c95913fe44031b6ca754914a78624a..cdf14d84b98fd9c7702082dd40661228b500f796 100644
--- a/Source/platform/BUILD.gn
+++ b/Source/platform/BUILD.gn
@@ -225,6 +225,7 @@ component("platform") {
   if (is_mac) {
     sources -= [
       "fonts/harfbuzz/FontHarfBuzz.cpp",
+      "fonts/harfbuzz/FontPlatformDataHarfBuzz.cpp",
       "fonts/harfbuzz/HarfBuzzFaceSkia.cpp",
       "fonts/opentype/OpenTypeTypes.h",
       "fonts/opentype/OpenTypeVerticalData.cpp",
@@ -261,6 +262,9 @@ component("platform") {
     ]
   } else {
     sources -= [
+      # FIXME: We will eventually compile this too, but for now it's
+      # only used on mac.
+      "fonts/FontPlatformData.cpp",
       "fonts/harfbuzz/HarfBuzzFaceCoreText.cpp",
       "geometry/cg/FloatPointCG.cpp",
       "geometry/cg/FloatRectCG.cpp",