LibJS: Allow "for" statement without curly braces around body

Libraries/LibJS/Parser.cpp

@@ -810,7 +810,7 @@ NonnullRefPtr<ForStatement> Parser::parse_for_statement()
 
     consume(TokenType::ParenClose);
 
-    auto body = parse_block_statement();
+    auto body = parse_statement();
 
     return create_ast_node<ForStatement>(move(init), move(test), move(update), move(body));
 }

Libraries/LibJS/Tests/for-no-curlies.js

@@ -0,0 +1,14 @@
+function assert(x) { if (!x) throw 1; }
+
+try {
+    var number = 0;
+
+    for (var i = 0; i < 3; ++i)
+        for (var j = 0; j < 3; ++j)
+            number++;
+
+    assert(number === 9);
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}