Revert "Add some support for the code-point code-unit distinction."

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 170 matching lines @@
   template<typename T>
   static RawString* New(const T* characters, intptr_t len);
   static RawString* New(const String& str);
   static RawString* New(const String& str,
                         intptr_t begin_index,
                         intptr_t length);
 
   // Returns char* of predefined symbol.
   static const char* Name(SymbolId symbol);
 
-  static RawString* FromCharCode(int32_t char_code);
+  static RawString* FromCharCode(uint32_t char_code);
 
  private:
   enum {
     kInitialVMIsolateSymtabSize = ((kMaxId + 15) & -16),
     kInitialSymtabSize = 256
   };
 
   // Add the string into the VM isolate symbol table.
   static void Add(const Array& symbol_table, const String& str);
 
@@ skipping 30 matching lines @@
   friend class SnapshotReader;
   friend class SnapshotWriter;
   friend class ApiMessageReader;
 
   DISALLOW_COPY_AND_ASSIGN(Symbols);
 };
 
 }  // namespace dart
 
 #endif  // VM_SYMBOLS_H_