Fix crash when combining text-emphasis with CSS variables

third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
index 47752a01be89c89a84a64deefdd8f9a8afbbccb0..58d56073356b6b316aafcb9b22c8c0153b77b757 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
@@ -58,7 +58,7 @@ static inline void filterProperties(bool important, const WillBeHeapVector<CSSPr
         const CSSProperty& property = input[i];
         if (property.isImportant() != important)
             continue;
-        const unsigned propertyIDIndex = property.id();
+        const unsigned propertyIDIndex = property.id() - firstCSSProperty;
         // All custom properties use the same CSSPropertyID so we can't remove repeated definitions
         if (property.id() != CSSPropertyVariable) {
             if (seenProperties.get(propertyIDIndex))