fix spelling in core libraries

sdk/lib/internal/symbol.dart

 // Copyright (c) 2013, 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.
 
 part of dart._internal;
 
 /**
  * Implementation of [core.Symbol].  This class uses the same name as
  * a core class so a user can't tell the difference.
  *
@@ skipping 27 matching lines @@
    *
    * It matches identifiers but not reserved words. The identifiers
    * may start with '_'.
    */
   static const String identifierRE =
       r'(?!' '$reservedWordRE' r'\b(?!\$))[a-zA-Z$_][\w$]*';
   /**
    * Source of RegExp matching a declarable operator names.
    *
    * The operators that can be declared using `operator` declarations are
-   * also the only ones allowed as symbols. The name of the oeprators is
+   * also the only ones allowed as symbols. The name of the operators is
    * the same as the operator itself except for unary minus, where the name
    * is "unary-".
    */
   static const String operatorRE =
       r'(?:[\-+*/%&|^]|\[\]=?|==|~/?|<[<=]?|>[>=]?|unary-)';
 
   // Grammar if symbols:
   //    symbol ::= qualifiedName | <empty>
   //    qualifiedName ::= publicIdentifier '.' qualifiedName | name
   //    name ::= publicIdentifier
@@ skipping 74 matching lines @@
 
   /**
    * Checks whether name is a valid symbol name.
    *
    * This test allows both private and non-private symbols.
    */
   static bool isValidSymbol(String name) {
     return (name.isEmpty || symbolPattern.hasMatch(name));
   }
 }