Add UseCounter features for cursor values -webkit-zoom-in/out

Source/core/css/parser/CSSPropertyParser.cpp

Index: Source/core/css/parser/CSSPropertyParser.cpp
diff --git a/Source/core/css/parser/CSSPropertyParser.cpp b/Source/core/css/parser/CSSPropertyParser.cpp
index a36a7c2e161c768092e069d40aa87cdbeb8b78d2..2b92b7b471725ed68224d94f1936d01477177946 100644
--- a/Source/core/css/parser/CSSPropertyParser.cpp
+++ b/Source/core/css/parser/CSSPropertyParser.cpp
@@ -667,6 +667,12 @@ bool CSSPropertyParser::parseValue(CSSPropertyID propId, bool important)
                 return false;
             value = m_valueList->next(); // comma
         }
+        if (value && m_context.useCounter()) {
+            if (value->id == CSSValueWebkitZoomIn)
+                m_context.useCounter()->count(UseCounter::PrefixedCursorZoomIn);
+            else if (value->id == CSSValueWebkitZoomOut)
+                m_context.useCounter()->count(UseCounter::PrefixedCursorZoomOut);

[Julien - ping for review, 2014/05/23 09:47:35]

Ideally we would want to send a deprecation message but IIRC this was hard to do
without having to touch the whole parsing logic as we need an extra argument
(Document / DOMWindow or ExecutionContext).

[philipj_slow, 2014/05/23 10:50:46]

Oh, hadn't noticed that countDeprecation is going to require an extra argument.
With some luck the usage will be so low that direct removal is possible,
otherwise we'll have to figure something out when deprecating this in a few
months time.

+        }
         if (list) {
             if (!value)
                 return false;