Return default value of true from TextEditor.getAutoHeight

When we need to check for unassigned in the deprecated code path, we
can just read the instance variable directly to avoid getting the
deafult.

Signed-off-by: Antonio Scandurra <as-cii@github.com>

spec/text-editor-spec.coffee

@@ -5507,8 +5507,8 @@ describe "TextEditor", ->
       expect(editor.getScrollPastEnd()).toBe(false)
 
   describe "auto height", ->
-    it "returns undefined by default but can be customized", ->
-      expect(editor.getAutoHeight()).toBeUndefined()
+    it "returns true by default but can be customized", ->
+      expect(editor.getAutoHeight()).toBe(true)
       editor.update({autoHeight: false})
       expect(editor.getAutoHeight()).toBe(false)
       editor.update({autoHeight: true})

src/text-editor-component.coffee

@@ -57,7 +57,7 @@ class TextEditorComponent
       cursorBlinkResumeDelay: @cursorBlinkResumeDelay
       stoppedScrollingDelay: 200
       lineTopIndex: lineTopIndex
-      autoHeight: @editor.getAutoHeight() ? true
+      autoHeight: @editor.getAutoHeight()
 
     @presenter.onDidUpdateState(@requestUpdate)
 
@@ -759,7 +759,7 @@ class TextEditorComponent
     # auto-height in certain circumstances. This is legacy behavior that we
     # would rather not implement, but we can't remove it without risking
     # breakage currently.
-    unless @editor.getAutoHeight()?
+    unless @editor.autoHeight?
       {position, top, bottom} = getComputedStyle(@hostElement)
       hasExplicitTopAndBottom = (position is 'absolute' and top isnt 'auto' and bottom isnt 'auto')
 

src/text-editor.coffee

@@ -3542,7 +3542,7 @@ class TextEditor extends Model
     Grim.deprecate("This is now a view method. Call TextEditorElement::getHeight instead.")
     @height
 
-  getAutoHeight: -> @autoHeight
+  getAutoHeight: -> @autoHeight ? true
 
   setWidth: (width, reentrant=false) ->
     if reentrant