Enabled using viewport on desktop browsers behind experimental flag

Source/core/page/Settings.in

 # FIXME: Add support for global settings.
 # FIXME: Add support for custom getters/setters.
 
 defaultTextEncodingName type=String
 editableLinkBehavior type=EditableLinkBehavior, initial=EditableLinkDefaultBehavior
 passwordEchoDurationInSeconds type=double, initial=1
 
 # Sets the magnification value for validation message timer.  If the
 # magnification value is N, a validation message disappears automatically after
 # <message length> * N / 1000 seconds.  If N is equal to or less than 0, a
 # validation message doesn't disappears automaticaly.
 validationMessageTimerMagnification type=int, initial=50
 
 # Number of pixels below which 2D canvas is rendered in software
 # even if hardware acceleration is enabled.
 # Hardware acceleration is useful for large canvases where it can avoid the
 # pixel bandwidth between the CPU and GPU. But GPU acceleration comes at
 # a price - extra back-buffer and texture copy. Small canvases are also
 # widely used for stylized fonts. Anti-aliasing text in hardware at that
 # scale is generally slower. So below a certain size it is better to
 # draw canvas in software.
 minimumAccelerated2dCanvasSize type=int, initial=257*256
 
-layoutFallbackWidth type=int, initial=980
+layoutFallbackWidth type=int, initial=0
 
 minimumFontSize type=int, initial=0, setNeedsStyleRecalcInAllFrames=1
 minimumLogicalFontSize type=int, initial=0, setNeedsStyleRecalcInAllFrames=1
 defaultFontSize type=int, initial=0, setNeedsStyleRecalcInAllFrames=1
 defaultFixedFontSize type=int, initial=0, setNeedsStyleRecalcInAllFrames=1
 
 editingBehaviorType type=EditingBehaviorType, initial=editingBehaviorTypeForPlatform()
 
 caretBrowsingEnabled initial=false
 localStorageEnabled initial=false
@@ skipping 95 matching lines @@
 smartInsertDeleteEnabled initial=defaultSmartInsertDeleteEnabled
 selectTrailingWhitespaceEnabled initial=defaultSelectTrailingWhitespaceEnabled
 
 selectionIncludesAltImageText initial=false
 
 # This setting enables touch based text selection and editing.
 touchEditingEnabled initial=false
 
 experimentalWebSocketEnabled initial=false
 pinchVirtualViewportEnabled initial=false