Improve google-ima shim script (#3899)

We made use of the google-ima shim script from uBlock in the
DuckDuckGo Privacy Essentials extension recently, but found a few
issues with website breakage. After debugging and fixing those[1], I
thought it would be worth sharing the improvements back again. Issues
we ran into:

- The AdDisplayContainer[2] constructor usually creates some DOM
  elements inside the given container. They are all nested within a
  DIV and some websites break when at least that top DIV element isn't
  created.
- While not documented (that I could see), the event listeners can be
  added using an array of event types. Some websites make use of that
  and then hang forever when the expected events aren't fired. This
  caused videos not to play on some websites.
- The Ad.prototype.getUniversalAdIds()[3] method should return an
  array of UniversalAdIdInfo Objects, instead of an Array of
  strings. When an array of strings are returned, some websites then
  break when the UniversalAdIdInfo's methods are missing.
- The UniversalAdIdInfo.prototype.getAdIdValue()[4] method had a typo
  in the name ("getAsIdValue") and was effectively missing. That
  caused some websites to break when the missing method was called.
- The google.ima.OmidVerificationVendor[5] Object was missing, which
  broke some websites that attempted to access it.

1 - 52f2999523
2 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima.AdDisplayContainer
3 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima.Ad#getUniversalAdIds
4 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima.UniversalAdIdInfo#getAdIdValue
5 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima#.OmidVerificationVendor

src/web_accessible_resources/google-ima.js

@@ -233,6 +233,12 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
   const ima = {};
 
   class AdDisplayContainer {
+    constructor(containerElement) {
+      const divElement = document.createElement("div");
+      divElement.style.setProperty("display", "none", "important");
+      divElement.style.setProperty("visibility", "collapse", "important");
+      containerElement.appendChild(divElement);
+    }
     destroy() {}
     initialize() {}
   }
@@ -335,19 +341,32 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
       }
     }
 
-    addEventListener(t, c) {
+    addEventListener(types, c) {
+      if (!Array.isArray(types)) {
+        types = [types];
+      }
+
+      for (const t of types) {
         if (!this.listeners.has(t)) {
           this.listeners.set(t, new Set());
         }
         this.listeners.get(t).add(c);
       }
+    }
 
-    removeEventListener(t, c) {
+    removeEventListener(types, c) {
+      if (!Array.isArray(types)) {
+        types = [types];
+      }
+
+      for (const t of types) {
         const typeSet = this.listeners.get(t);
-      if (!typeSet) { return; }
+        if (typeSet) {
           typeSet.delete(c);
         }
       }
+    }
+  }
 
   class AdsLoader extends EventHandler {
     constructor() {
@@ -553,7 +572,7 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
       return "unknown";
     }
     getUniversalAdIds() {
-      return [""];
+      return [new UniversalAdIdInfo()];
     }
     getUniversalAdIdValue() {
       return "unknown";
@@ -765,7 +784,7 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
     getAdIdRegistry() {
       return "";
     }
-    getAdIsValue() {
+    getAdIdValue() {
       return "";
     }
   }
@@ -793,12 +812,12 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
       FULL: "full",
       LIMITED: "limited",
     },
-    OmidVerificationVendor: new Proxy({}, {
-        get(target, prop) {
-            if ( typeof prop === 'number' ) { return ''; }
-            return 0;
-        }
-    }),
+    OmidVerificationVendor: {
+      1: "OTHER",
+      2: "GOOGLE",
+      GOOGLE: 2,
+      OTHER: 1
+    },
     settings: new ImaSdkSettings(),
     UiElements: {
       AD_ATTRIBUTION: "adAttribution",