Fix issue #2677 : Labels should not get quick info

Author: GuillaumeSalles

src/services/services.ts

@@ -3798,6 +3798,10 @@ module ts {
                 // Try getting just type at this position and show
                 switch (node.kind) {
                     case SyntaxKind.Identifier:
+                        if(isLabelName(node)){
+                            return undefined;
+                        }
+                    // Fall through.
                     case SyntaxKind.PropertyAccessExpression:
                     case SyntaxKind.QualifiedName:
                     case SyntaxKind.ThisKeyword:

tests/cases/fourslash/noQuickInfoForLabel.ts

@@ -0,0 +1,11 @@
+/// <reference path='fourslash.ts'/>
+
+//// /*1*/label : while(true){
+////     break /*2*/label;
+//// }
+
+goTo.marker('1');
+verify.not.quickInfoExists();
+
+goTo.marker('2');
+verify.not.quickInfoExists();