Bug 1289058 - Null check principals before holding them in JS::FirstS…

…ubsumedFrame; r=jimb

js/src/jit-test/tests/saved-stacks/bug-1289058.js

@@ -0,0 +1,13 @@
+const g1 = newGlobal({});
+const g2 = newGlobal(newGlobal);
+g1.g2obj = g2.eval("new Object");
+g1.evaluate(`
+  const global = this;
+  function capture(shouldIgnoreSelfHosted = true) {
+    return captureFirstSubsumedFrame(global.g2obj, shouldIgnoreSelfHosted);
+  }
+  (function iife1() {
+    const captureTrueStack = capture(true);
+  }());
+`, {
+});

js/src/jsapi.h

@@ -5933,7 +5933,8 @@ struct FirstSubsumedFrame
       , principals(p)
       , ignoreSelfHosted(ignoreSelfHostedFrames)
     {
-        JS_HoldPrincipals(principals);
+        if (principals)
+            JS_HoldPrincipals(principals);
     }
 
     // No copying because we want to avoid holding and dropping principals