Bug 1224580. Copy of URLSearchParams should not copy its observer pointer. r=baku

dom/base/URLSearchParams.cpp

@@ -315,7 +315,7 @@ URLSearchParams::URLSearchParams(nsISupports* aParent,
                                  const URLSearchParams& aOther)
   : mParams(new URLParams(*aOther.mParams.get()))
   , mParent(aParent)
-  , mObserver(aOther.mObserver)
+  , mObserver(nullptr)
 {
 }
 

dom/base/test/test_urlSearchParams.html

@@ -300,6 +300,20 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=887836
     runTest();
   }
 
+  function testCopyConstructor() {
+    var url = new URL("http://example.com/");
+    var p = url.searchParams;
+    var q = new URLSearchParams(p);
+    q.set("a", "b");
+    is(url.href, "http://example.com/",
+       "Messing with copy of URLSearchParams should not affect URL");
+    p.set("c", "d");
+    is(url.href, "http://example.com/?c=d",
+       "Messing with URLSearchParams should affect URL");
+
+    runTest();
+  }
+
   var tests = [
     testSimpleURLSearchParams,
     testCopyURLSearchParams,
@@ -314,6 +328,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=887836
     testSet,
     testIterable,
     testZeroHandling,
+    testCopyConstructor,
   ];
 
   function runTest() {