Add strong mode type checking pass.

lib/ast.dart

Index: lib/ast.dart
diff --git a/lib/ast.dart b/lib/ast.dart
index aa2228581e456fe3164b650aeee3e4b5514198d3..d76f98615f93798872683adc1ac2c06c6a11406b 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);