Add strong mode type checking pass.

lib/ast.dart

 // Copyright (c) 2016, 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.
 
 /// -----------------------------------------------------------------------
 ///                           ERROR HANDLING
 /// -----------------------------------------------------------------------
 ///
 /// As a rule of thumb, errors that can be detected statically are handled by
 /// the frontend, typically by translating the erroneous code into a 'throw' or
@@ skipping 2232 matching lines @@
   DartType typeArgument; // Not null, defaults to DynamicType.
   final List<Expression> expressions;
 
   ListLiteral(this.expressions,
       {this.typeArgument: const DynamicType(), this.isConst: false}) {
     assert(typeArgument != null);
     setParents(expressions, this);
   }
 
   DartType getStaticType(TypeEnvironment types) {
-    return types.listType(typeArgument);
+    return types.literalListType(typeArgument);
   }
 
   accept(ExpressionVisitor v) => v.visitListLiteral(this);
 
   visitChildren(Visitor v) {
     typeArgument?.accept(v);
     visitList(expressions, v);
   }
 
   transformChildren(Transformer v) {
@@ skipping 11 matching lines @@
   MapLiteral(this.entries,
       {this.keyType: const DynamicType(),
       this.valueType: const DynamicType(),
       this.isConst: false}) {
     assert(keyType != null);
     assert(valueType != null);
     setParents(entries, this);
   }
 
   DartType getStaticType(TypeEnvironment types) {
-    return types.mapType(keyType, valueType);
+    return types.literalMapType(keyType, valueType);
   }
 
   accept(ExpressionVisitor v) => v.visitMapLiteral(this);
 
   visitChildren(Visitor v) {
     keyType?.accept(v);
     valueType?.accept(v);
     visitList(entries, v);
   }
 
@@ skipping 1346 matching lines @@
 
   @override
   defaultTreeNode(TreeNode node) {
     if (node == child) {
       return replacement;
     } else {
       return node;
     }
   }
 }