Apply matchMedia to the top frame (prebid#3612)

* Apply matchMedia to the top frame

In case Prebid.js is called from within an iFrame, matchMedia should be applied to window.top, not the containing iFrame.
This PR falls back to the legacy behavior in case of unfriendly iFrames.

* Spec update

src/sizeMapping.js

@@ -1,5 +1,5 @@
 import { config } from './config';
-import {logWarn, isPlainObject, deepAccess, deepClone} from './utils';
+import {logWarn, isPlainObject, deepAccess, deepClone, getWindowTop} from './utils';
 import includes from 'core-js/library/fn/array/includes';
 
 let sizeConfig = [];
@@ -123,7 +123,17 @@ function evaluateSizeConfig(configs) {
       typeof config === 'object' &&
       typeof config.mediaQuery === 'string'
     ) {
-      if (matchMedia(config.mediaQuery).matches) {
+      let ruleMatch = false;
+
+      try {
+        ruleMatch = getWindowTop().matchMedia(config.mediaQuery).matches;
+      } catch (e) {
+        logWarn('Unfriendly iFrame blocks sizeConfig from being correctly evaluated');
+
+        ruleMatch = matchMedia(config.mediaQuery).matches;
+      }
+
+      if (ruleMatch) {
         if (Array.isArray(config.sizesSupported)) {
           results.shouldFilter = true;
         }

test/spec/sizeMapping_spec.js

@@ -60,6 +60,13 @@ describe('sizeMapping', function () {
 
     matchMediaOverride = {matches: false};
 
+    sandbox.stub(utils.getWindowTop(), 'matchMedia').callsFake((...args) => {
+      if (typeof matchMediaOverride === 'function') {
+        return matchMediaOverride.apply(utils.getWindowTop(), args);
+      }
+      return matchMediaOverride;
+    });
+
     sandbox.stub(window, 'matchMedia').callsFake((...args) => {
       if (typeof matchMediaOverride === 'function') {
         return matchMediaOverride.apply(window, args);