Don't cascade maximized windows

Fixes #10335

src/browser/atom-application.coffee

@@ -369,6 +369,7 @@ class AtomApplication
   # Get the dimensions for opening a new window by cascading as appropriate to
   # the platform.
   getDimensionsForNewWindow: ->
+    return if (@focusedWindow() ? @lastFocusedWindow)?.isMaximized() and process.platform isnt 'darwin'
     dimensions = (@focusedWindow() ? @lastFocusedWindow)?.getDimensions()
     offset = @getWindowOffsetForCurrentPlatform()
     if dimensions? and offset?

src/browser/atom-window.coffee

@@ -212,6 +212,8 @@ class AtomWindow
 
   isFocused: -> @browserWindow.isFocused()
 
+  isMaximized: -> @browserWindow.isMaximized()
+
   isMinimized: -> @browserWindow.isMinimized()
 
   isWebViewFocused: -> @browserWindow.isWebViewFocused()