Cache the typeface instead of the font data in the test font selector (…

…flutter#3576)

The font data includes attributes such as the font size and will be
different for each font description.

Fixes flutter/flutter#9289

runtime/test_font_selector.cc

@@ -6,7 +6,6 @@
 #include "flutter/lib/ui/ui_dart_state.h"
 #include "flutter/runtime/test_font_data.h"
 #include "flutter/sky/engine/platform/fonts/SimpleFontData.h"
-#include "third_party/skia/include/core/SkTypeface.h"
 
 namespace blink {
 
@@ -22,26 +21,21 @@ TestFontSelector::~TestFontSelector() = default;
 PassRefPtr<FontData> TestFontSelector::getFontData(
     const FontDescription& fontDescription,
     const AtomicString& familyName) {
-  if (test_font_data_ != nullptr) {
-    return test_font_data_;
+  if (!test_typeface_) {
+    test_typeface_ = SkTypeface::MakeFromStream(GetTestFontData().release());
   }
 
-  auto typeface = SkTypeface::MakeFromStream(GetTestFontData().release());
-
   bool syntheticBold = (fontDescription.weight() >= FontWeight600 ||
                         fontDescription.isSyntheticBold());
   bool syntheticItalic = (fontDescription.style() ||
                           fontDescription.isSyntheticItalic());
-  FontPlatformData platform_data(typeface, "Ahem",
+  FontPlatformData platform_data(test_typeface_, "Ahem",
                                  fontDescription.effectiveFontSize(),
                                  syntheticBold, syntheticItalic,
                                  fontDescription.orientation(),
                                  fontDescription.useSubpixelPositioning());
 
-  test_font_data_ =
-      SimpleFontData::create(platform_data, CustomFontData::create());
-
-  return test_font_data_;
+  return SimpleFontData::create(platform_data, CustomFontData::create());
 }
 
 void TestFontSelector::willUseFontData(const FontDescription&,

runtime/test_font_selector.h

@@ -8,6 +8,7 @@
 #include "flutter/sky/engine/platform/fonts/FontSelector.h"
 #include "flutter/sky/engine/wtf/RefPtr.h"
 #include "lib/ftl/macros.h"
+#include "third_party/skia/include/core/SkTypeface.h"
 
 namespace blink {
 
@@ -29,7 +30,7 @@ class TestFontSelector : public FontSelector {
   void fontCacheInvalidated() override;
 
  private:
-  WTF::RefPtr<FontData> test_font_data_;
+  sk_sp<SkTypeface> test_typeface_;
 
   TestFontSelector();