Add --no-declaration-casts option to analyzer.

pkg/analyzer/lib/src/generated/resolver.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.src.generated.resolver;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_resolution_map.dart';
@@ skipping 829 matching lines @@
    */
   bool _checkForInvalidAssignment(Expression lhs, Expression rhs) {
     if (lhs == null || rhs == null) {
       return false;
     }
     VariableElement leftVariableElement = ErrorVerifier.getVariableElement(lhs);
     DartType leftType = (leftVariableElement == null)
         ? ErrorVerifier.getStaticType(lhs)
         : leftVariableElement.type;
     DartType staticRightType = ErrorVerifier.getStaticType(rhs);
-    if (!_typeSystem.isAssignableTo(staticRightType, leftType)) {
+    if (!_typeSystem.isAssignableTo(staticRightType, leftType,
+        isDeclarationCast: true)) {
       // The warning was generated on this rhs
       return false;
     }
     // Test for, and then generate the hint
     DartType bestRightType = rhs.bestType;
     if (leftType != null && bestRightType != null) {
-      if (!_typeSystem.isAssignableTo(bestRightType, leftType)) {
+      if (!_typeSystem.isAssignableTo(bestRightType, leftType,
+          isDeclarationCast: true)) {
         _errorReporter.reportTypeErrorForNode(
             HintCode.INVALID_ASSIGNMENT, rhs, [bestRightType, leftType]);
         return true;
       }
     }
     return false;
   }
 
   void _checkForInvalidFactory(MethodDeclaration decl) {
     // Check declaration.
@@ skipping 9790 matching lines @@
       return null;
     }
     if (identical(node.staticElement, variable)) {
       if (node.inSetterContext()) {
         result = true;
       }
     }
     return null;
   }
 }