Add incremental test.

tests/cases/unittests/incrementalParser.ts

@@ -606,7 +606,7 @@ module ts {
 
         it('Modifier added to accessor',() => {
             var source =
-                "class C {\
+"class C {\
     set Bar(bar:string) {}\
 }\
 var o2 = { set Foo(val:number) { } };";
@@ -620,7 +620,7 @@ var o2 = { set Foo(val:number) { } };";
 
         it('Insert parameter ahead of parameter',() => {
             var source =
-                "alert(100);\
+"alert(100);\
 \
 class OverloadedMonster {\
 constructor();\
@@ -634,6 +634,19 @@ constructor(name) { }\
             compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 0);
         });
 
+        it('Insert declare modifier before module',() => {
+            var source =
+"module mAmbient {\
+module m3 { }\
+}";
+
+            var oldText = ScriptSnapshot.fromString(source);
+            var index = 0;
+            var newTextAndChange = withInsert(oldText, index, "declare ");
+
+            compareTrees(oldText, newTextAndChange.text, newTextAndChange.textChangeRange, 0);
+        });
+
         // Simulated typing tests.
 
         it('Type extends clause 1',() => {