CSS Custom Properties (Variables)

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index 50f7ddd9d5dc6d439de33d0130e9fd31c4123e7a..06e99bcb72d495b0ea050a335238e32fb846cf7c 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -59,6 +59,7 @@
 #include "core/css/StyleRuleImport.h"
 #include "core/css/StyleSheetContents.h"
 #include "core/css/resolver/AnimatedStyleBuilder.h"
+#include "core/css/resolver/CSSVariableResolver.h"
 #include "core/css/resolver/MatchResult.h"
 #include "core/css/resolver/MediaQueryResult.h"
 #include "core/css/resolver/ScopedStyleResolver.h"
@@ -645,6 +646,9 @@ PassRefPtr<ComputedStyle> StyleResolver::styleForElement(Element* element, const
     if (state.style()->hasRemUnits())
         document().styleEngine().setUsesRemUnit(true);
 
+    if (state.style()->variables())
+        document().styleEngine().setUsesVariables(true);
+
     // Now return the style.
     return state.takeStyle();
 }
@@ -1168,6 +1172,11 @@ static bool shouldIgnoreTextTrackAuthorStyle(Document& document)
 template <CSSPropertyPriority priority>
 void StyleResolver::applyAllProperty(StyleResolverState& state, CSSValue* allValue, bool inheritedOnly)
 {
+    // The 'all' property doesn't apply to variables:
+    // https://drafts.csswg.org/css-variables/#defining-variables
+    if (priority == ResolveVariables)
+        return;
+
     unsigned startCSSProperty = CSSPropertyPriorityData<priority>::first();
     unsigned endCSSProperty = CSSPropertyPriorityData<priority>::last();
 
@@ -1312,6 +1321,14 @@ void StyleResolver::applyMatchedProperties(StyleResolverState& state, const Matc
         applyInheritedOnly = true;
     }
 
+    // TODO(leviw): We need the proper bit for tracking whether we need to do this work.
+    if (RuntimeEnabledFeatures::cssVariablesEnabled()) {
+        applyMatchedProperties<ResolveVariables>(state, matchResult, false, matchResult.beginAuthor(), matchResult.endAuthor(), applyInheritedOnly);
+        applyMatchedProperties<ResolveVariables>(state, matchResult, true, matchResult.beginAuthor(), matchResult.endAuthor(), applyInheritedOnly);
+        // TODO(leviw): stop recalculating every time
+        CSSVariableResolver::resolveVariableDefinitions(state);
+    }
+
     // Now we have all of the matched rules in the appropriate order. Walk the rules and apply
     // high-priority properties first, i.e., those properties that other properties depend on.
     // The order is (1) high-priority not important, (2) high-priority important, (3) normal not important