Fix scroll width calculation when longest line is folded

With the presenter we started clipping screen positions prior to
translating them to pixel positions. This interacts with the current
clipping behavior on folded lines (which should change) where the cursor
is always clipped to 0. So when the longest line was also folded we
were miscalculating the width. 🙈!

The removal of clipping also causes us to calculate the width based on
the trailing whitespace of soft-wrapped lines, which I actually think
is an improvement but it is slightly different.

spec/text-editor-presenter-spec.coffee

@@ -498,6 +498,11 @@ describe "TextEditorPresenter", ->
 
           expect(presenter.getState().content.scrollWidth).toBe 10 * editor.getMaxScreenLineLength() + 1
 
+        it "isn't clipped to 0 when the longest line is folded (regression)", ->
+          presenter = buildPresenter(contentFrameWidth: 50, baseCharacterWidth: 10)
+          editor.foldBufferRow(0)
+          expect(presenter.getState().content.scrollWidth).toBe 10 * editor.getMaxScreenLineLength() + 1
+
       describe ".scrollTop", ->
         it "tracks the value of ::scrollTop", ->
           presenter = buildPresenter(scrollTop: 10, lineHeight: 10, explicitHeight: 20)

src/text-editor-component.coffee

@@ -349,15 +349,15 @@ class TextEditorComponent
 
     if Math.abs(wheelDeltaX) > Math.abs(wheelDeltaY)
       # Scrolling horizontally
-      previousScrollLeft = @editor.getScrollLeft()
+      previousScrollLeft = @presenter.getScrollLeft()
       @presenter.setScrollLeft(previousScrollLeft - Math.round(wheelDeltaX * @scrollSensitivity))
-      event.preventDefault() unless previousScrollLeft is @editor.getScrollLeft()
+      event.preventDefault() unless previousScrollLeft is @presenter.getScrollLeft()
     else
       # Scrolling vertically
       @presenter.setMouseWheelScreenRow(@screenRowForNode(event.target))
-      previousScrollTop = @presenter.scrollTop
+      previousScrollTop = @presenter.getScrollTop()
       @presenter.setScrollTop(previousScrollTop - Math.round(wheelDeltaY * @scrollSensitivity))
-      event.preventDefault() unless previousScrollTop is @editor.getScrollTop()
+      event.preventDefault() unless previousScrollTop is @presenter.getScrollTop()
 
   onScrollViewScroll: =>
     if @mounted

src/text-editor-presenter.coffee

@@ -541,7 +541,8 @@ class TextEditorPresenter
 
     if @baseCharacterWidth?
       oldContentWidth = @contentWidth
-      @contentWidth = @pixelPositionForScreenPosition([@model.getLongestScreenRow(), Infinity]).left
+      clip = @model.tokenizedLineForScreenRow(@model.getLongestScreenRow())?.isSoftWrapped()
+      @contentWidth = @pixelPositionForScreenPosition([@model.getLongestScreenRow(), @model.getMaxScreenLineLength()], clip).left
       @contentWidth += 1 unless @model.isSoftWrapped() # account for cursor width
 
     if @contentHeight isnt oldContentHeight
@@ -691,6 +692,9 @@ class TextEditorPresenter
       @updateCustomGutterDecorationState()
       @updateOverlaysState()
 
+  getScrollTop: ->
+    @scrollTop
+
   didStartScrolling: ->
     if @stoppedScrollingTimeoutId?
       clearTimeout(@stoppedScrollingTimeoutId)
@@ -720,6 +724,9 @@ class TextEditorPresenter
       @updateCursorsState() unless oldScrollLeft?
       @updateOverlaysState()
 
+  getScrollLeft: ->
+    @scrollLeft
+
   setHorizontalScrollbarHeight: (horizontalScrollbarHeight) ->
     unless @measuredHorizontalScrollbarHeight is horizontalScrollbarHeight
       oldHorizontalScrollbarHeight = @measuredHorizontalScrollbarHeight