Fix regression: folds can be destroyed by clicking them

spec/app/editor-spec.coffee

@@ -1943,9 +1943,11 @@ describe "Editor", ->
     describe "when a fold placeholder line is clicked", ->
       it "removes the associated fold and places the cursor at its beginning", ->
         editor.setCursorBufferPosition([3,0])
-        editor.trigger 'editor:fold-current-row'
+        editSession.createFold(3, 5)
 
-        editor.find('.fold.line').mousedown()
+        foldLine = editor.find('.line.fold')
+        expect(foldLine).toExist()
+        foldLine.mousedown()
 
         expect(editor.find('.fold')).not.toExist()
         expect(editor.find('.fold-marker')).not.toExist()

src/app/display-buffer.coffee

@@ -107,6 +107,10 @@ class DisplayBuffer
         @buffer.markRange([[startRow, 0], [endRow, Infinity]], @foldMarkerAttributes())
     @foldForMarker(foldMarker)
 
+  # Destroys the fold with the given id
+  destroyFoldWithId: (id) ->
+    @foldsByMarkerId[id]?.destroy()
+
   # Removes any folds found that contain the given buffer row.
   #
   # bufferRow - The buffer row {Number} to check against

src/app/edit-session.coffee

@@ -540,6 +540,10 @@ class EditSession
   createFold: (startRow, endRow) ->
     @displayBuffer.createFold(startRow, endRow)
 
+  # {Delegates to: DisplayBuffer.destroyFoldWithId}
+  destroyFoldWithId: (id) ->
+    @displayBuffer.destroyFoldWithId(id)
+
   # {Delegates to: DisplayBuffer.destroyFoldsContainingBufferRow}
   destroyFoldsContainingBufferRow: (bufferRow) ->
     @displayBuffer.destroyFoldsContainingBufferRow(bufferRow)

src/app/editor.coffee

@@ -621,7 +621,7 @@ class Editor extends View
       false if @isFocused
 
     @renderedLines.on 'mousedown', '.fold.line', (e) =>
-      @destroyFold($(e.currentTarget).attr('fold-id'))
+      @activeEditSession.destroyFoldWithId($(e.currentTarget).attr('fold-id'))
       false
 
     @renderedLines.on 'mousedown', (e) =>

src/app/fold.coffee

@@ -7,12 +7,14 @@ Point = require 'point'
 # Their creation is managed by the {DisplayBuffer}.
 module.exports =
 class Fold
+  id: null
   displayBuffer: null
   marker: null
 
   ### Internal ###
 
   constructor: (@displayBuffer, @marker) ->
+    @id = @marker.id
     @displayBuffer.foldsByMarkerId[@marker.id] = this
     @updateDisplayBuffer()
     @marker.on 'destroyed', => @destroyed()