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

runtime/vm/symbols.cc

Index: runtime/vm/symbols.cc
diff --git a/runtime/vm/symbols.cc b/runtime/vm/symbols.cc
index e89426948726624bc61f44763073a7754eb0ef86..9c1b5df60ff5fd3d1e72cb86856b83c8c9bfc9f0 100644
--- a/runtime/vm/symbols.cc
+++ b/runtime/vm/symbols.cc
@@ -97,7 +97,7 @@ RawString* Symbols::New(const char* str) {
   Utf8::Type type;
   intptr_t str_len = strlen(str);
   const uint8_t* utf8_array = reinterpret_cast<const uint8_t*>(str);
-  intptr_t len = Utf8::CodePointCount(utf8_array, str_len, &type);
+  intptr_t len = Utf8::CodeUnitCount(utf8_array, str_len, &type);
   Zone* zone = Isolate::Current()->current_zone();
   if (len == 0) {
     return Symbols::New(reinterpret_cast<uint8_t*>(NULL), 0);
@@ -148,7 +148,7 @@ RawString* Symbols::New(const T* characters, intptr_t len) {
 
 template RawString* Symbols::New(const uint8_t* characters, intptr_t len);
 template RawString* Symbols::New(const uint16_t* characters, intptr_t len);
-template RawString* Symbols::New(const uint32_t* characters, intptr_t len);
+template RawString* Symbols::New(const int32_t* characters, intptr_t len);
 
 
 RawString* Symbols::New(const String& str) {
@@ -277,7 +277,7 @@ template intptr_t Symbols::FindIndex(const Array& symbol_table,
                                      intptr_t len,
                                      intptr_t hash);
 template intptr_t Symbols::FindIndex(const Array& symbol_table,
-                                     const uint32_t* characters,
+                                     const int32_t* characters,
                                      intptr_t len,
                                      intptr_t hash);