Move JSSyntaxRegExp to core as a private member. This removes the last refrences to dart:coreimpl.

runtime/vm/symbols.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_SYMBOLS_H_
 #define VM_SYMBOLS_H_
 
 #include "vm/object.h"
 #include "vm/snapshot_ids.h"
 
@@ skipping 96 matching lines @@
   V(Double, "_Double")                                                         \
   V(Bool, "bool")                                                              \
   V(ObjectArray, "_ObjectArray")                                               \
   V(GrowableObjectArray, "_GrowableObjectArray")                               \
   V(ImmutableArray, "_ImmutableArray")                                         \
   V(OneByteString, "_OneByteString")                                           \
   V(TwoByteString, "_TwoByteString")                                           \
   V(ExternalOneByteString, "_ExternalOneByteString")                           \
   V(ExternalTwoByteString, "_ExternalTwoByteString")                           \
   V(Stacktrace, "Stacktrace")                                                  \
-  V(JSSyntaxRegExp, "JSSyntaxRegExp")                                          \
+  V(JSSyntaxRegExp, "_JSSyntaxRegExp")                                         \
   V(Object, "Object")                                                          \
   V(_Int8Array, "_Int8Array")                                                  \
   V(_Uint8Array, "_Uint8Array")                                                \
   V(_Int16Array, "_Int16Array")                                                \
   V(_Uint16Array, "_Uint16Array")                                              \
   V(_Int32Array, "_Int32Array")                                                \
   V(_Uint32Array, "_Uint32Array")                                              \
   V(_Int64Array, "_Int64Array")                                                \
   V(_Uint64Array, "_Uint64Array")                                              \
   V(_Float32Array, "_Float32Array")                                            \
@@ skipping 98 matching lines @@
   friend class SnapshotReader;
   friend class SnapshotWriter;
   friend class ApiMessageReader;
 
   DISALLOW_COPY_AND_ASSIGN(Symbols);
 };
 
 }  // namespace dart
 
 #endif  // VM_SYMBOLS_H_