Use %pure-parser in grammar files to make Bison 3 happy.

This avoids a "deprecated directive, use ‘%pure-parser’ [-Wdeprecated]"
warning in css/CSSGrammar.y and xml/XPathGrammar.y when building with
Bison 3.

Review URL: https://codereview.chromium.org/217423011

git-svn-id: svn://svn.chromium.org/blink/trunk@170525 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/css/CSSGrammar.y

@@ -60,7 +60,7 @@ using namespace HTMLNames;
 
 %}
 
-%pure_parser
+%pure-parser
 
 %parse-param { BisonCSSParser* parser }
 %lex-param { BisonCSSParser* parser }

third_party/WebKit/Source/core/xml/XPathGrammar.y

@@ -51,7 +51,7 @@ using namespace XPath;
 
 %}
 
-%pure_parser
+%pure-parser
 %parse-param { WebCore::XPath::Parser* parser }
 
 %union