[Squad] style_ in StyleResolverState is always mutable.

The style_ member of StyleResolverState is a ComputedStyle which is
being built. There's no reason to have a separate Mutable* method to
access it, we can always return it non-const.

Bug: 813068
Change-Id: I7282441f2cac2e37ace98d0ee0709baf1ec656ea
Reviewed-on: https://chromium-review.googlesource.com/1026682Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553517}

third_party/blink/renderer/core/css/resolver/style_adjuster.cc

@@ -517,7 +517,7 @@ void StyleAdjuster::AdjustComputedStyle(StyleResolverState& state,
                                         Element* element) {
   DCHECK(state.LayoutParentStyle());
   DCHECK(state.ParentStyle());
-  ComputedStyle& style = state.MutableStyleRef();
+  ComputedStyle& style = state.StyleRef();
   const ComputedStyle& parent_style = *state.ParentStyle();
   const ComputedStyle& layout_parent_style = *state.LayoutParentStyle();
 

third_party/blink/renderer/core/css/resolver/style_resolver.cc

@@ -780,7 +780,7 @@ scoped_refptr<AnimatableValue> StyleResolver::CreateAnimatableValueSnapshot(
     StyleBuilder::ApplyProperty(property, state, *value);
     state.GetFontBuilder().CreateFont(
         state.GetDocument().GetStyleEngine().GetFontSelector(),
-        state.MutableStyleRef());
+        state.StyleRef());
   }
   return CSSAnimatableValueFactory::Create(property, *state.Style());
 }
@@ -1041,8 +1041,7 @@ scoped_refptr<ComputedStyle> StyleResolver::StyleForText(Text* text_node) {
 
 void StyleResolver::UpdateFont(StyleResolverState& state) {
   state.GetFontBuilder().CreateFont(
-      GetDocument().GetStyleEngine().GetFontSelector(),
-      state.MutableStyleRef());
+      GetDocument().GetStyleEngine().GetFontSelector(), state.StyleRef());
   state.SetConversionFontSizes(CSSToLengthConversionData::FontSizes(
       state.Style(), state.RootElementStyle()));
   state.SetConversionZoom(state.Style()->EffectiveZoom());

third_party/blink/renderer/core/css/resolver/style_resolver_state.h

@@ -87,11 +87,12 @@ class CORE_EXPORT StyleResolverState {
   void SetStyle(scoped_refptr<ComputedStyle>);
   const ComputedStyle* Style() const { return style_.get(); }
   ComputedStyle* Style() { return style_.get(); }
+  ComputedStyle& StyleRef() {
+    DCHECK(style_);
+    return *style_;
+  }
   scoped_refptr<ComputedStyle> TakeStyle();
 
-  ComputedStyle& MutableStyleRef() const { return *style_; }
-  const ComputedStyle& StyleRef() const { return MutableStyleRef(); }
-
   const CSSToLengthConversionData& CssToLengthConversionData() const {
     return css_to_length_conversion_data_;
   }