fix crash in signature help

src/compiler/types.ts

@@ -257,7 +257,7 @@ module ts {
         LastTypeNode = ParenthesizedType,
         FirstPunctuation = OpenBraceToken,
         LastPunctuation = CaretEqualsToken,
-        FirstToken = EndOfFileToken,
+        FirstToken = Unknown,
         LastToken = TypeKeyword,
         FirstTriviaToken = SingleLineCommentTrivia,
         LastTriviaToken = WhitespaceTrivia,

src/services/utilities.ts

@@ -280,10 +280,6 @@ module ts {
     }
 
     function nodeHasTokens(n: Node): boolean {
-        if (n.kind === SyntaxKind.Unknown) {
-            return false;
-        }
-
         // If we have a token or node that has a non-zero width, it must have tokens.
         // Note, that getWidth() does not take trivia into account.
         return n.getWidth() !== 0;

tests/cases/fourslash/signatureHelpWithUnknown.ts

@@ -0,0 +1,6 @@
+/// <reference path='fourslash.ts'/>
+
+////eval(\/*1*/
+
+goTo.marker("1");
+verify.signatureHelpCountIs(1);