Update XML doc to make it clearer that 'compiler.emulatedStack' should no longer be used.

Review at http://gwt-code-reviews.appspot.com/1462804

Review by: robertvawter@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@10469 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/user/src/com/google/gwt/core/EmulateJsStack.gwt.xml b/user/src/com/google/gwt/core/EmulateJsStack.gwt.xml
index ae928e4..099e536 100644
--- a/user/src/com/google/gwt/core/EmulateJsStack.gwt.xml
+++ b/user/src/com/google/gwt/core/EmulateJsStack.gwt.xml
@@ -17,8 +17,7 @@
 <module>
   <inherits name="com.google.gwt.core.Core" />
 
-  <!-- Legacy property, use 'compiler.stackMode' instead -->
-  <!-- If set to true, emulated stack frames will be emitted into the JS -->
+  <!-- Legacy property. Do NOT use. See 'compiler.stackMode' instead. -->
   <define-property name="compiler.emulatedStack" values="true,false" />
   <set-property name="compiler.emulatedStack" value="false" />