Support use of external strings as inputs to LoadCodeUnitsInstr.

runtime/vm/object.cc

 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 13619 matching lines @@
     return TypedData::ElementSizeInBytes(cid);
   }
   switch (cid) {
     case kArrayCid:
     case kImmutableArrayCid:
       return Array::kBytesPerElement;
     case kOneByteStringCid:
       return OneByteString::kBytesPerElement;
     case kTwoByteStringCid:
       return TwoByteString::kBytesPerElement;
+    case kExternalOneByteStringCid:
+      return ExternalOneByteString::kBytesPerElement;
+    case kExternalTwoByteStringCid:
+      return ExternalTwoByteString::kBytesPerElement;
     default:
       UNIMPLEMENTED();
       return 0;
   }
 }
 
 
 intptr_t Instance::DataOffsetFor(intptr_t cid) {
   if (RawObject::IsExternalTypedDataClassId(cid)) {
     // Elements start at offset 0 of the external data.
@@ skipping 6806 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart