Clean up handling of autosizing state changes.

Source/core/page/Page.cpp

Index: Source/core/page/Page.cpp
diff --git a/Source/core/page/Page.cpp b/Source/core/page/Page.cpp
index bf754e02fb7af76e3e3c43c8c9d19040afd8b2fb..270065c4283d3697d16c6d9c18795e2775f2a2fb 100644
--- a/Source/core/page/Page.cpp
+++ b/Source/core/page/Page.cpp
@@ -52,6 +52,7 @@
 #include "core/page/StorageClient.h"
 #include "core/page/ValidationMessageClient.h"
 #include "core/page/scrolling/ScrollingCoordinator.h"
+#include "core/rendering/FastTextAutosizer.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/TextAutosizer.h"
 #include "core/storage/StorageNamespace.h"
@@ -486,10 +487,10 @@ void Page::settingsChanged(SettingsDelegate::ChangeType changeType)
         }
         break;
     case SettingsDelegate::TextAutosizingChange:
-        if (RuntimeEnabledFeatures::fastTextAutosizingEnabled()) {
-            // FTA needs both setNeedsRecalcStyle and setNeedsLayout after a setting change.
-            setNeedsRecalcStyleInAllFrames();
-            setNeedsLayoutInAllFrames();
+        if (!mainFrame())
+            break;
+        if (FastTextAutosizer* textAutosizer = mainFrame()->document()->fastTextAutosizer()) {
+            textAutosizer->updatePageInfoInAllFrames();
         } else {
             for (LocalFrame* frame = mainFrame(); frame; frame = frame->tree().traverseNext()) {
                 if (TextAutosizer* textAutosizer = frame->document()->textAutosizer())