Remove ScrollRestoration runtime flag (status=stable)

BUG=402536

Review-Url: https://codereview.chromium.org/2340453002
Cr-Commit-Position: refs/heads/master@{#418786}

third_party/WebKit/Source/core/frame/History.cpp

@@ -93,7 +93,7 @@ SerializedScriptValue* History::stateInternal() const
 void History::setScrollRestoration(const String& value)
 {
     ASSERT(value == "manual"  || value == "auto");
-    if (!m_frame || !m_frame->loader().client() || !RuntimeEnabledFeatures::scrollRestorationEnabled())
+    if (!m_frame || !m_frame->loader().client())
         return;
 
     HistoryScrollRestorationType scrollRestoration = value == "manual" ? ScrollRestorationManual : ScrollRestorationAuto;
@@ -113,7 +113,7 @@ String History::scrollRestoration()
 
 HistoryScrollRestorationType History::scrollRestorationInternal() const
 {
-    if (m_frame && RuntimeEnabledFeatures::scrollRestorationEnabled()) {
+    if (m_frame) {
         if (HistoryItem* historyItem = m_frame->loader().currentItem())
             return historyItem->scrollRestorationType();
     }

third_party/WebKit/Source/core/frame/History.idl

@@ -30,7 +30,7 @@ enum ScrollRestoration {"auto", "manual"};
 [
 ] interface History {
     readonly attribute unsigned long length;
-    [RuntimeEnabled=ScrollRestoration, Measure] attribute ScrollRestoration scrollRestoration;
+    [Measure] attribute ScrollRestoration scrollRestoration;
     // TODO(foolip): The SerializedScriptValue type should be any.
     [CachedAttribute=stateChanged] readonly attribute SerializedScriptValue state;
     [CallWith=ExecutionContext] void go(optional long delta = 0);

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in

@@ -248,7 +248,6 @@ VisibilityChangeOnUnload status=experimental
 XSLT status=stable
 smil status=stable
 ScrollCustomization
-ScrollRestoration status=stable
 AutoplayMutedVideos settable_from_internals=True
 VisualViewportAPI status=experimental
 WakeLock status=experimental