Remove unnecessary casts and general code clean-up

pkg/analyzer/lib/src/dart/constant/value.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.
 
 /**
  * The implementation of the class [DartObject].
  */
 library analyzer.src.dart.constant.value;
 
 import 'dart:collection';
@@ skipping 354 matching lines @@
         throw new EvaluationException(
             CompileTimeErrorCode.CONST_EVAL_TYPE_BOOL_NUM_STRING);
       }
     }
     return new DartObjectImpl(
         typeProvider.boolType, _state.equalEqual(rightOperand._state));
   }
 
   @override
   DartObject getField(String name) {
-    if (_state is GenericState) {
-      return (_state as GenericState).fields[name];
+    InstanceState state = _state;
+    if (state is GenericState) {
+      return state.fields[name];
     }
     return null;
   }
 
   /**
    * Return the result of invoking the '>' operator on this object with the
    * [rightOperand]. The [typeProvider] is the type provider used to find known
    * types.
    *
    * Throws an [EvaluationException] if the operator is not appropriate for an
@@ skipping 258 matching lines @@
       return new DartObjectImpl(typeProvider.doubleType, result);
     } else if (result is NumState) {
       return new DartObjectImpl(typeProvider.numType, result);
     }
     // We should never get here.
     throw new IllegalStateException("times returned a ${result.runtimeType}");
   }
 
   @override
   bool toBoolValue() {
-    if (_state is BoolState) {
-      return (_state as BoolState).value;
+    InstanceState state = _state;
+    if (state is BoolState) {
+      return state.value;
     }
     return null;
   }
 
   @override
   double toDoubleValue() {
-    if (_state is DoubleState) {
-      return (_state as DoubleState).value;
+    InstanceState state = _state;
+    if (state is DoubleState) {
+      return state.value;
     }
     return null;
   }
 
   @override
   int toIntValue() {
-    if (_state is IntState) {
-      return (_state as IntState).value;
+    InstanceState state = _state;
+    if (state is IntState) {
+      return state.value;
     }
     return null;
   }
 
   @override
   List<DartObject> toListValue() {
-    if (_state is ListState) {
-      return (_state as ListState)._elements;
+    InstanceState state = _state;
+    if (state is ListState) {
+      return state._elements;
     }
     return null;
   }
 
   @override
   Map<DartObject, DartObject> toMapValue() {
-    if (_state is MapState) {
-      return (_state as MapState)._entries;
+    InstanceState state = _state;
+    if (state is MapState) {
+      return state._entries;
     }
     return null;
   }
 
   @override
   String toString() => "${type.displayName} ($_state)";
 
   @override
   String toStringValue() {
-    if (_state is StringState) {
-      return (_state as StringState).value;
+    InstanceState state = _state;
+    if (state is StringState) {
+      return state.value;
     }
     return null;
   }
 
   @override
   String toSymbolValue() {
-    if (_state is SymbolState) {
-      return (_state as SymbolState).value;
+    InstanceState state = _state;
+    if (state is SymbolState) {
+      return state.value;
     }
     return null;
   }
 
   @override
   DartType toTypeValue() {
-    if (_state is TypeState) {
-      Element element = (_state as TypeState)._element;
+    InstanceState state = _state;
+    if (state is TypeState) {
+      Element element = state._element;
       if (element is TypeDefiningElement) {
         return element.type;
       }
     }
     return null;
   }
 }
 
 /**
  * The state of an object representing a double.
@@ skipping 2083 matching lines @@
       return BoolState.from(_element == rightElement);
     } else if (rightOperand is DynamicState) {
       return BoolState.UNKNOWN_VALUE;
     }
     return BoolState.FALSE_STATE;
   }
 
   @override
   String toString() => _element == null ? "-unknown-" : _element.name;
 }