Remove dart backend

test/dart_codegen/expect/_internal/symbol.dart

-part of dart._internal;
- class Symbol implements core.Symbol {final String _name;
- static const String reservedWordRE = r'(?:assert|break|c(?:a(?:se|tch)|lass|on(?:st|tinue))|d(?:efault|o)|' r'e(?:lse|num|xtends)|f(?:alse|inal(?:ly)?|or)|i[fns]|n(?:ew|ull)|' r'ret(?:hrow|urn)|s(?:uper|witch)|t(?:h(?:is|row)|r(?:ue|y))|' r'v(?:ar|oid)|w(?:hile|ith))';
- static const String publicIdentifierRE = r'(?!' '$reservedWordRE' r'\b(?!\$))[a-zA-Z$][\w$]*';
- static const String identifierRE = r'(?!' '$reservedWordRE' r'\b(?!\$))[a-zA-Z$_][\w$]*';
- static const String operatorRE = r'(?:[\-+*/%&|^]|\[\]=?|==|~/?|<[<=]?|>[>=]?|unary-)';
- static final RegExp publicSymbolPattern = new RegExp('^(?:$operatorRE\$|$publicIdentifierRE(?:=?\$|[.](?!\$)))+?\$');
- static final RegExp symbolPattern = new RegExp('^(?:$operatorRE\$|$identifierRE(?:=?\$|[.](?!\$)))+?\$');
- external const Symbol(String name);
- const Symbol.unvalidated(this._name);
- Symbol.validated(String name) : this._name = validatePublicSymbol(name);
- bool operator ==(Object other) => other is Symbol && _name == other._name;
- int get hashCode {
-  const arbitraryPrime = 664597;
-   return 0x1fffffff & (arbitraryPrime * _name.hashCode);
-  }
- toString() => 'Symbol("$_name")';
- static String getName(Symbol symbol) => symbol._name;
- static String validatePublicSymbol(String name) {
-  if (name.isEmpty || publicSymbolPattern.hasMatch(name)) return name;
-   if (name.startsWith('_')) {
-    throw new ArgumentError('"$name" is a private identifier');
-    }
-   throw new ArgumentError('"$name" is not a valid (qualified) symbol name');
-  }
- static bool isValidSymbol(String name) {
-  return (name.isEmpty || symbolPattern.hasMatch(name));
-  }
-}