Fix break statement in presence of labels

In this snippet...

    for (;;) label: break

...the break statement jumped back to the start of the loop instead of
*out* of the loop.

Fixes: #741

Author: bnoordhuis

quickjs.c

@@ -24917,9 +24917,7 @@ static __exception int emit_break(JSParseState *s, JSAtom name, int is_cont)
             emit_goto(s, OP_goto, top->label_cont);
             return 0;
         }
-        if (!is_cont &&
-            top->label_break != -1 &&
-            (name == JS_ATOM_NULL || top->label_name == name)) {
+        if (!is_cont && top->label_break != -1 && top->label_name == name) {
             emit_goto(s, OP_goto, top->label_break);
             return 0;
         }

tests/bug741.js

@@ -0,0 +1,19 @@
+import {assert} from "./assert.js"
+
+while (1) label: break
+
+var i = 0
+while (i < 3) label: {
+    if (i > 0)
+        break
+    i++
+}
+assert(i, 1)
+
+for (;;) label: break
+
+for (i = 0; i < 3; i++) label: {
+    if (i > 0)
+        break
+}
+assert(i, 1)