Fix for issue 7089 (Symbols::New was not quite working correctly

vm/symbols.h

Index: vm/symbols.h
===================================================================
--- vm/symbols.h	(revision 15671)
+++ vm/symbols.h	(working copy)
@@ -177,10 +177,23 @@
   // Get number of symbols in an isolate's symbol table.
   static intptr_t Size(Isolate* isolate);
 
-  // Helper functions to create a symbol given a string or set of characters.
-  static RawString* New(const char* str);
-  template<typename T>
-  static RawString* New(const T* characters, intptr_t len);
+  // Creates a Symbol given a C string that is assumed to contain
+  // UTF-8 encoded characters and '\0' is considered a termination character.
+  // TODO(7123) - Rename this to FromCString(....).
+  static RawString* New(const char* cstr);
+
+  // Creates a new Symbol from an array of UTF-8 encoded characters.
+  static RawString* FromUTF8(const uint8_t* utf8_array, intptr_t len);
+
+  // Creates a new Symbol from an array of Latin-1 encoded characters.
+  static RawString* FromLatin1(const uint8_t* latin1_array, intptr_t len);
+
+  // Creates a new Symbol from an array of UTF-16 encoded characters.
+  static RawString* FromUTF16(const uint16_t* utf16_array, intptr_t len);
+
+  // Creates a new Symbol from an array of UTF-32 encoded characters.
+  static RawString* FromUTF32(const int32_t* utf32_array, intptr_t len);
+
   static RawString* New(const String& str);
   static RawString* New(const String& str,
                         intptr_t begin_index,
@@ -201,6 +214,10 @@
     kInitialSymtabSize = 256
   };
 
+  // Helper functions to create a symbol given a string or set of characters.
+  template<typename T>
+  static RawString* NewSymbol(const T* characters, intptr_t len);
+
   // Add the string into the VM isolate symbol table.
   static void Add(const Array& symbol_table, const String& str);
 
@@ -234,6 +251,7 @@
   // List of symbols that are stored in the vm isolate for easy access.
   static RawString* predefined_[kMaxId];
 
+  friend class String;
   friend class SnapshotReader;
   friend class SnapshotWriter;
   friend class ApiMessageReader;