jscript: Fixed conflict in Block statement that caused problems with empty blocks.

dlls/jscript/parser.y

@@ -325,8 +325,8 @@ StatementList_opt
 
 /* ECMA-262 3rd Edition    12.1 */
 Block
-        : '{' StatementList_opt '}'
-                                { $$ = new_block_statement(ctx, $2); }
+        : '{' StatementList '}' { $$ = new_block_statement(ctx, $2); }
+        | '{' '}'               { $$ = new_block_statement(ctx, NULL) }
 
 /* ECMA-262 3rd Edition    12.2 */
 VariableStatement

dlls/jscript/tests/lang.js

@@ -175,6 +175,10 @@ if(true)
     tmp = 1;
 ok(tmp === 1, "tmp !== 1, if(true) not evaluated?");
 
+if(false) {
+}else {
+}
+
 var obj3 = { prop1: 1,  prop2: typeof(false) };
 ok(obj3.prop1 === 1, "obj3.prop1 is not 1");
 ok(obj3.prop2 === "boolean", "obj3.prop2 is not \"boolean\"");