Issue 4901. Tweak for dart:core check

compiler/java/com/google/dart/compiler/resolver/Elements.java

Index: compiler/java/com/google/dart/compiler/resolver/Elements.java
diff --git a/compiler/java/com/google/dart/compiler/resolver/Elements.java b/compiler/java/com/google/dart/compiler/resolver/Elements.java
index 075fa1d2d98f43997d0447bae43d5c8edeb647e6..0e3efaf72de76c9666c6e76531e65b30187397fb 100644
--- a/compiler/java/com/google/dart/compiler/resolver/Elements.java
+++ b/compiler/java/com/google/dart/compiler/resolver/Elements.java
@@ -705,7 +705,7 @@ static FieldElementImplementation fieldFromNode(DartField node,
       LibrarySource library = dartSource.getLibrary();
       if (library != null) {
         String libraryName = library.getName();
-        return libraryName.startsWith("dart://") && libraryName.endsWith("/" + name);
+        return libraryName.endsWith("/core/" + name);
       }
     }
     return false;