Migrate WTF::Vector::append() to ::push_back() [part 3 of N]

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

Index: third_party/WebKit/Source/core/css/CSSVariableData.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSVariableData.cpp b/third_party/WebKit/Source/core/css/CSSVariableData.cpp
index ae18409d28669627bee8d5152709184eb61e717d..07b022425c1b634728540c2af59ec57f2668e81b 100644
--- a/third_party/WebKit/Source/core/css/CSSVariableData.cpp
+++ b/third_party/WebKit/Source/core/css/CSSVariableData.cpp
@@ -29,10 +29,10 @@ void CSSVariableData::updateTokens(const CSSParserTokenRange& range) {
     if (token.hasStringBacking()) {
       unsigned length = token.value().length();
       StringView string(currentOffset, length);
-      m_tokens.append(token.copyWithUpdatedString(string));
+      m_tokens.push_back(token.copyWithUpdatedString(string));
       currentOffset += length;
     } else {
-      m_tokens.append(token);
+      m_tokens.push_back(token);
     }
   }
   ASSERT(currentOffset ==