Merge pull request #2497 from Microsoft/decorators_emit

Emit decorators when --target ES3

Author: rbuckton

src/compiler/emitter.ts

@@ -3757,10 +3757,6 @@ module ts {
             }
 
             function emitDecoratorsOfClass(node: ClassDeclaration) {
-                if (languageVersion < ScriptTarget.ES5) {
-                    return;
-                }
-
                 emitDecoratorsOfMembers(node, /*staticFlag*/ 0);
                 emitDecoratorsOfMembers(node, NodeFlags.Static);
                 emitDecoratorsOfConstructor(node);