Enable Legacy TLS interstitial by default on iOS

Bug: 1113359
Change-Id: I4640e25113cd6cd7ec0031f6a08a743ce3a6b07d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2611905Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Chris Thompson <cthomp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#840389}

ios/web/common/features.mm

@@ -43,8 +43,8 @@ const base::Feature kPreserveScrollViewProperties{
 
 const base::Feature kScrollToTextIOS{"ScrollToTextIOS",
                                      base::FEATURE_ENABLED_BY_DEFAULT};
-const base::Feature kIOSLegacyTLSInterstitial{
-    "IOSLegacyTLSInterstitial", base::FEATURE_DISABLED_BY_DEFAULT};
+const base::Feature kIOSLegacyTLSInterstitial{"IOSLegacyTLSInterstitial",
+                                              base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kWebViewNativeContextMenu{
     "WebViewNativeContextMenu", base::FEATURE_DISABLED_BY_DEFAULT};