Update String methods.

tool/input_sdk/private/js_rti.dart

Index: tool/input_sdk/private/js_rti.dart
diff --git a/tool/input_sdk/private/js_rti.dart b/tool/input_sdk/private/js_rti.dart
index 4eb1f17a33419dd42bc523244c17c85f877483ec..549cd33aed30d78b38cb916ba4a62b9b260b40f8 100644
--- a/tool/input_sdk/private/js_rti.dart
+++ b/tool/input_sdk/private/js_rti.dart
@@ -11,13 +11,13 @@ Type getRuntimeType(var object) =>
 
 /// Returns the property [index] of the JavaScript array [array].
 getIndex(var array, int index) {
-  assert_(isJsArray(array));
+  assert(isJsArray(array));
   return JS('var', r'#[#]', array, index);
 }
 
 /// Returns the length of the JavaScript array [array].
 int getLength(var array) {
-  assert_(isJsArray(array));
+  assert(isJsArray(array));
   return JS('int', r'#.length', array);
 }