Bug 1817680 - Repeat GC when needed; r=dom-storage-reviewers,asuth

Differential Revision: https://phabricator.services.mozilla.com/D188561

dom/indexedDB/test/helpers.js

@@ -313,7 +313,11 @@ function scheduleGC() {
 function* assertEventuallyWithGC(conditionFunctor, message) {
   const maxGC = 100;
   for (let i = 0; i < maxGC; ++i) {
-    if (conditionFunctor()) {
+    let result =
+      conditionFunctor.constructor.name === "GeneratorFunction"
+        ? yield* conditionFunctor()
+        : conditionFunctor();
+    if (result) {
       ok(true, message + " (after " + i + " garbage collections)");
       return;
     }

dom/indexedDB/test/test_file_os_delete.html

@@ -93,10 +93,15 @@
     // Flush pending file deletions before checking usage.
     flushPendingFileDeletions();
 
-    getCurrentUsage(grabFileUsageAndContinueHandler);
-    let endUsage = yield undefined;
+    yield* assertEventuallyWithGC(
+      function* () {
+        getCurrentUsage(grabFileUsageAndContinueHandler);
+        let endUsage = yield undefined;
 
-    is(endUsage, startUsage, "OS files deleted");
+        return endUsage == startUsage;
+      },
+      "OS files deleted"
+    );
 
     finishTest();
   }