Issue 1606/1108. The 'native' keyword is supposed to only be allowed in core libraries.

compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java

Index: compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java
diff --git a/compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java b/compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java
index 319c8955563914ed089199906268a977c8dab00b..8ce8ee3c3f169eb2b97f1407bca6d9f96e249ac8 100644
--- a/compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java
+++ b/compiler/java/com/google/dart/compiler/parser/ParserErrorCode.java
@@ -49,7 +49,9 @@ public enum ParserErrorCode implements ErrorCode {
   EXPECTED_TOKEN("Unexpected token '%s' (expected '%s')"),
   EXPECTED_VAR_FINAL_OR_TYPE("Expected 'var', 'final' or type"),
   EXPORTED_FUNCTIONS_MUST_BE_STATIC("Exported functions must be static"),
-  EXTENDED_NATIVE_CLASS("Native classes must not extend other classes"),
+  NATIVE_MUST_NOT_EXTEND("Native classes must not extend other classes"),
+  NATIVE_ONLY_CLASS("Native keyword can be specified only for classes"),
+  NATIVE_ONLY_CORE_LIB("Native keyword can be used only in corelib"),
   FACTORY_CANNOT_BE_ABSTRACT("A factory cannot be abstract"),
   FACTORY_CANNOT_BE_STATIC("A factory cannot be static"),
   FACTORY_MEMBER_IN_INTERFACE("Factory members are not allowed in interfaces"),