Do not use a Blink feature flag for Manifest.

Source/core/html/HTMLLinkElement.cpp

Index: Source/core/html/HTMLLinkElement.cpp
diff --git a/Source/core/html/HTMLLinkElement.cpp b/Source/core/html/HTMLLinkElement.cpp
index a9729a6a5dfedd8766498c37c486ddee4727594d..b49e883657acf2068112b5cab0cccc1ee9d42922 100644
--- a/Source/core/html/HTMLLinkElement.cpp
+++ b/Source/core/html/HTMLLinkElement.cpp
@@ -210,7 +210,7 @@ LinkResource* HTMLLinkElement::linkResourceToProcess()
     if (!m_link) {
         if (m_relAttribute.isImport()) {
             m_link = LinkImport::create(this);
-        } else if (m_relAttribute.isManifest() && RuntimeEnabledFeatures::manifestEnabled()) {
+        } else if (m_relAttribute.isManifest()) {
             m_link = LinkManifest::create(this);
         } else {
             OwnPtrWillBeRawPtr<LinkStyle> link = LinkStyle::create(this);