Assume media elements with no Content-Length header to be of size 0

Related issue:
- https://github.com/uBlockOrigin/uBlock-issues/issues/543

src/js/pagestore.js

@@ -440,11 +440,11 @@ PageStore.prototype.toggleNetFilteringSwitch = function(url, scope, state) {
 /******************************************************************************/
 
 PageStore.prototype.injectLargeMediaElementScriptlet = function() {
-    this.largeMediaTimer = null;
-    µb.scriptlets.injectDeep(
-        this.tabId,
-        'load-large-media-interactive'
-    );
+    vAPI.tabs.injectScript(this.tabId, {
+        file: '/js/scriptlets/load-large-media-interactive.js',
+        allFrames: true,
+        runAt: 'document_idle',
+    });
     µb.contextMenu.update(this.tabId);
 };
 
@@ -714,10 +714,10 @@ PageStore.prototype.filterLargeMediaElement = function(fctxt, size) {
 
     this.largeMediaCount += 1;
     if ( this.largeMediaTimer === null ) {
-        this.largeMediaTimer = vAPI.setTimeout(
-            this.injectLargeMediaElementScriptlet.bind(this),
-            500
-        );
+        this.largeMediaTimer = vAPI.setTimeout(( ) => {
+            this.largeMediaTimer = null;
+            this.injectLargeMediaElementScriptlet();
+        }, 500);
     }
 
     if ( µb.logger.enabled ) {

src/js/traffic.js

@@ -907,10 +907,13 @@ const injectCSP = function(fctxt, pageStore, responseHeaders) {
 //   "Block elements by size"
 
 const foilLargeMediaElement = function(fctxt, pageStore, responseHeaders) {
-    const i = headerIndexFromName('content-length', responseHeaders);
-    if ( i === -1 ) { return; }
+    let size = 0;
+    if ( µBlock.userSettings.largeMediaSize !== 0 ) {
+        const i = headerIndexFromName('content-length', responseHeaders);
+        if ( i === -1 ) { return; }
+        size = parseInt(responseHeaders[i].value, 10) || 0;
+    }
 
-    const size = parseInt(responseHeaders[i].value, 10) || 0;
     const result = pageStore.filterLargeMediaElement(fctxt, size);
     if ( result === 0 ) { return; }