Replace scalarlist optimizations and split external array loads into two IL instructions.

runtime/lib/string.cc

 // Copyright (c) 2011, 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/bootstrap_natives.h"
 
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
@@ skipping 197 matching lines @@
       const Array& args = Array::Handle(Array::New(1));
       args.SetAt(0, elem);
       Exceptions::ThrowByType(Exceptions::kArgument, args);
     }
   }
   return String::ConcatAll(strings);
 }
 
 
 DEFINE_NATIVE_ENTRY(StringBuffer_createStringFromUint16Array, 3) {
-  GET_NON_NULL_NATIVE_ARGUMENT(Uint16Array, codeUnits,
-                               arguments->NativeArgAt(0));
+  GET_NON_NULL_NATIVE_ARGUMENT(TypedData, codeUnits, arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, length, arguments->NativeArgAt(1));
   GET_NON_NULL_NATIVE_ARGUMENT(Bool, isLatin1, arguments->NativeArgAt(2));
   intptr_t array_length = codeUnits.Length();
   intptr_t length_value = length.Value();
   if (length_value < 0 || length_value > array_length) {
     const Array& args = Array::Handle(Array::New(1));
     args.SetAt(0, length);
     Exceptions::ThrowByType(Exceptions::kRange, args);
   }
   const String& result = isLatin1.value()
       ? String::Handle(OneByteString::New(length_value, Heap::kNew))
       : String::Handle(TwoByteString::New(length_value, Heap::kNew));
   NoGCScope no_gc;
 
-  uint16_t* data_position = reinterpret_cast<uint16_t*>(codeUnits.ByteAddr(0));
+  uint16_t* data_position = reinterpret_cast<uint16_t*>(codeUnits.DataAddr(0));
   String::Copy(result, 0, data_position, length_value);
   return result.raw();
 }
 
 }  // namespace dart