Add strong mode type checking pass.

lib/ast.dart

Index: lib/ast.dart
diff --git a/lib/ast.dart b/lib/ast.dart
index d3ac0535120ef6a424910824a82164e3c91924dd..dc9cb6d746dcd22c33fdaef7ddef60f81a46a564 100644
--- a/lib/ast.dart
+++ b/lib/ast.dart
@@ -2250,7 +2250,7 @@ class ListLiteral extends Expression {
   }
 
   DartType getStaticType(TypeEnvironment types) {
-    return types.listType(typeArgument);
+    return types.literalListType(typeArgument);
   }
 
   accept(ExpressionVisitor v) => v.visitListLiteral(this);
@@ -2282,7 +2282,7 @@ class MapLiteral extends Expression {
   }
 
   DartType getStaticType(TypeEnvironment types) {
-    return types.mapType(keyType, valueType);
+    return types.literalMapType(keyType, valueType);
   }
 
   accept(ExpressionVisitor v) => v.visitMapLiteral(this);