Make Analyzer, VM and dart2js accept URI strings as part-of library identifier.

pkg/analyzer/test/generated/parser_test.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.test.generated.parser_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
@@ skipping 3442 matching lines @@
   }
 
   void test_nonIdentifierLibraryName_library() {
     CompilationUnit unit = parseCompilationUnit(
         "library 'lib';", [ParserErrorCode.NON_IDENTIFIER_LIBRARY_NAME]);
     expect(unit, isNotNull);
   }
 
   void test_nonIdentifierLibraryName_partOf() {
     CompilationUnit unit = parseCompilationUnit(
-        "part of 'lib';", [ParserErrorCode.NON_IDENTIFIER_LIBRARY_NAME]);
+        "part of 3;", [ParserErrorCode.MISSING_NAME_IN_PART_OF_DIRECTIVE,
+                       ParserErrorCode.UNEXPECTED_TOKEN]);
     expect(unit, isNotNull);
   }
 
   void test_nonPartOfDirectiveInPart_after() {
     parseCompilationUnit("part of l; part 'f.dart';",
         [ParserErrorCode.NON_PART_OF_DIRECTIVE_IN_PART]);
   }
 
   void test_nonPartOfDirectiveInPart_before() {
     parseCompilationUnit("part 'f.dart'; part of m;",
@@ skipping 11282 matching lines @@
     expect(functionType.returnType, isNotNull);
     expect(functionType.typeParameters, isNull);
   }
 
   void test_parseTypeAlias_genericFunction_withDocComment() {
     createParser('/// Doc\ntypedef F = bool Function();');
     var typeAlias = parseFullCompilationUnitMember() as GenericTypeAlias;
     expectCommentText(typeAlias.documentationComment, '/// Doc');
   }
 }