jscript: Fix shift/reduce conflict in IfStatement rule.

The famous "dangling else" problem.

dlls/jscript/parser.y

@@ -253,6 +253,9 @@ static source_elements_t *source_elements_add_function(source_elements_t*,functi
 %type <literal> BooleanLiteral
 %type <srcptr> KFunction
 
+%nonassoc LOWER_THAN_ELSE
+%nonassoc kELSE
+
 %%
 
 /* ECMA-262 3rd Edition    14 */
@@ -389,7 +392,7 @@ ExpressionStatement
 IfStatement
         : kIF '(' Expression ')' Statement kELSE Statement
                                 { $$ = new_if_statement(ctx, $3, $5, $7); }
-        | kIF '(' Expression ')' Statement
+        | kIF '(' Expression ')' Statement %prec LOWER_THAN_ELSE
                                 { $$ = new_if_statement(ctx, $3, $5, NULL); }
 
 /* ECMA-262 3rd Edition    12.6 */

dlls/jscript/tests/lang.js

@@ -773,6 +773,18 @@ try {
     ok(false, "deleteTest not throwed exception?");
 }catch(ex) {}
 
+if (false)
+    if (true)
+        ok(false, "if evaluated");
+    else
+        ok(false, "else should be associated with nearest if statement");
+
+if (true)
+    if (false)
+        ok(false, "if evaluated");
+    else
+        ok(true, "else should be associated with nearest if statement");
+
 ok(isNaN(0.5) === false, "isNaN(0.5) !== false");
 ok(isNaN() === true, "isNaN() !== true");