Mixed Content: Remove redundant pref from tests.

LayoutTests/http/tests/fetch/resources/init.js

Index: LayoutTests/http/tests/fetch/resources/init.js
diff --git a/LayoutTests/http/tests/fetch/resources/init.js b/LayoutTests/http/tests/fetch/resources/init.js
index 347aad61f50c6abf42365082a142b4c4b69bc784..f9bc2e392ff7f8a2c9d1a2a91f50cf2f45b4e683 100644
--- a/LayoutTests/http/tests/fetch/resources/init.js
+++ b/LayoutTests/http/tests/fetch/resources/init.js
@@ -1,17 +1,4 @@
 if (window.testRunner) {
-  // In Chromium we need to change the setting to disallow displaying
-  // insecure contents.
-
-  // By default, LayoutTest content_shell returns allowed for
-  // "Should fetching request be blocked as mixed content?" at Step 5:
-  // https://w3c.github.io/webappsec/specs/mixedcontent/#should-block-fetch
-  // > If the user agent has been instructed to allow mixed content
-  // Turning the switch below to false makes this condition above false, and
-  // make content_shell to run into Step 7 to test mixed content blocking.
-  testRunner.overridePreference('WebKitAllowRunningInsecureContent', false);
-  //FIXME: to be removed.
-  //testRunner.overridePreference('WebKitAllowDisplayingInsecureContent', true);
-
   // Accept all cookies.
   testRunner.setAlwaysAcceptCookies(true);
 }