Scale to legibleScale if double tap would barely zoom in from zoomed out state.

Source/web/WebViewImpl.h

Index: Source/web/WebViewImpl.h
diff --git a/Source/web/WebViewImpl.h b/Source/web/WebViewImpl.h
index e900e9cba74d1bbc832d93579765c768454b157a..70632dd5a0f68dc159bc5d55ce6e2906627495cb 100644
--- a/Source/web/WebViewImpl.h
+++ b/Source/web/WebViewImpl.h
@@ -526,7 +526,7 @@ public:
     // a plugin can update its own zoom, say because of its own UI.
     void fullFramePluginZoomLevelChanged(double zoomLevel);
 
-    void computeScaleAndScrollForBlockRect(const WebRect& blockRect, float padding, float& scale, WebPoint& scroll, bool& doubleTapShouldZoomOut);
+    void computeScaleAndScrollForBlockRect(const WebRect& blockRect, float padding, float defaultScaleWhenAlreadyLegible, float& scale, WebPoint& scroll);
     WebCore::Node* bestTapNode(const WebCore::PlatformGestureEvent& tapEvent);
     void enableTapHighlight(const WebCore::PlatformGestureEvent& tapEvent);
     void computeScaleAndScrollForFocusedNode(WebCore::Node* focusedNode, float& scale, WebCore::IntPoint& scroll, bool& needAnimation);
@@ -573,6 +573,7 @@ public:
     WebVector<WebCompositionUnderline> compositionUnderlines() const;
 
 private:
+    float legibleScale() const;
     void refreshPageScaleFactorAfterLayout();
     void setUserAgentPageScaleConstraints(WebCore::PageScaleConstraints newConstraints);
     float clampPageScaleFactorToLimits(float) const;