Bug 1805511 - Add targeting for default PDF and HTML handlers r=nalexander,omc-reviewers,emcminn

This also fixes a bug in ASRouter devtools that prevented evaluation of
expressions containing nested promises. Objects containing promises are now
correctly serialized to the ASRouter devtools and expressions evaluate
correctly.

Differential Revision: https://phabricator.services.mozilla.com/D169408

browser/components/newtab/lib/ASRouter.jsm

@@ -1140,14 +1140,26 @@ class _ASRouter {
    * and ASRouter._getMessagesContext parameters and values
    */
   async getTargetingParameters(environment, localContext) {
-    const targetingParameters = {};
-    for (const param of Object.keys(environment)) {
-      targetingParameters[param] = await environment[param];
-    }
-    for (const param of Object.keys(localContext)) {
-      targetingParameters[param] = await localContext[param];
+    // Resolve objects that may contain promises.
+    async function resolve(object) {
+      const target = {};
+
+      for (const param of Object.keys(object)) {
+        target[param] = await object[param];
+
+        if (typeof target[param] === "object" && target[param] !== null) {
+          target[param] = await resolve(target[param]);
+        }
+      }
+
+      return target;
     }
 
+    const targetingParameters = {
+      ...(await resolve(environment)),
+      ...(await resolve(localContext)),
+    };
+
     return targetingParameters;
   }