Support nested calc()

third_party/WebKit/Source/core/css/CSSCalculationValue.cpp

Index: third_party/WebKit/Source/core/css/CSSCalculationValue.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSCalculationValue.cpp b/third_party/WebKit/Source/core/css/CSSCalculationValue.cpp
index 58f4167022620b0aea6319e110536fcc456396d3..c7e375279a6bc95a9f89a946802562f7eff8a464 100644
--- a/third_party/WebKit/Source/core/css/CSSCalculationValue.cpp
+++ b/third_party/WebKit/Source/core/css/CSSCalculationValue.cpp
@@ -636,7 +636,7 @@ private:
         if (checkDepthAndIndex(&depth, tokens) != OK)
             return false;
 
-        if (tokens.peek().type() == LeftParenthesisToken) {
+        if (tokens.peek().type() == LeftParenthesisToken || tokens.peek().functionId() == CSSValueCalc) {
             CSSParserTokenRange innerRange = tokens.consumeBlock();
             tokens.consumeWhitespace();
             innerRange.consumeWhitespace();