Bug 1219554 - Enable the browser_memory_clear_snapshots.js test on DEBUG builds; r=jsantell

devtools/client/memory/test/browser/browser.ini

@@ -9,7 +9,6 @@ support-files =
 [browser_memory_allocationStackBreakdown_01.js]
 [browser_memory_breakdowns_01.js]
 [browser_memory_clear_snapshots.js]
-    skip-if = debug # bug 1219554
 [browser_memory_diff_01.js]
     skip-if = debug # bug 1219554
 [browser_memory_dominator_trees_01.js]

devtools/client/memory/test/browser/browser_memory_clear_snapshots.js

@@ -16,9 +16,12 @@ this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   is(snapshotEls.length, 0, "No snapshots visible");
 
   info("Take two snapshots");
-  yield takeSnapshot(panel.panelWin);
-  yield takeSnapshot(panel.panelWin);
-  yield waitUntilSnapshotState(gStore, [states.SAVED_CENSUS, states.SAVED_CENSUS]);
+  takeSnapshot(panel.panelWin);
+  takeSnapshot(panel.panelWin);
+  yield waitUntilState(gStore, state =>
+    state.snapshots.length === 2 &&
+    state.snapshots[0].state === states.SAVED_CENSUS &&
+    state.snapshots[1].state === states.SAVED_CENSUS);
 
   snapshotEls = document.querySelectorAll("#memory-tool-container .list li");
   is(snapshotEls.length, 2, "Two snapshots visible");