RenderTextHarfBuzz: Add support for multi line text selection.

ui/views/style/platform_style_mac.mm

Index: ui/views/style/platform_style_mac.mm
diff --git a/ui/views/style/platform_style_mac.mm b/ui/views/style/platform_style_mac.mm
index 97caa9544e594a9d7f5941b5d9e0d045adb7fda0..4e07484e09028f50267ef9ee6733c3df515457f9 100644
--- a/ui/views/style/platform_style_mac.mm
+++ b/ui/views/style/platform_style_mac.mm
@@ -23,7 +23,6 @@ const int PlatformStyle::kMinLabelButtonWidth = 32;
 const int PlatformStyle::kMinLabelButtonHeight = 30;
 const bool PlatformStyle::kDefaultLabelButtonHasBoldFont = false;
 const bool PlatformStyle::kDialogDefaultButtonCanBeCancel = false;
-const bool PlatformStyle::kTextDragVerticallyDragsToEnd = true;
 const bool PlatformStyle::kSelectWordOnRightClick = true;
 const bool PlatformStyle::kTreeViewHasFocusRing = true;
 const bool PlatformStyle::kTreeViewSelectionPaintsEntireRow = true;