Pass buffer from event to TextBuffer::removeBuffer

Previously only the last buffer would be destroyed since the buffer
from the loop variable was being used.

src/project.coffee

@@ -34,7 +34,7 @@ class Project extends telepath.Model
   # Private: Called by telepath.
   attached: ->
     for buffer in @buffers.getValues()
-      buffer.once 'destroyed', => @removeBuffer(buffer)
+      buffer.once 'destroyed', (buffer) => @removeBuffer(buffer)
 
     @openers = []
     @editors = []

src/text-buffer.coffee

@@ -86,7 +86,7 @@ class TextBuffer extends telepath.Model
       @file?.off()
       @unsubscribe()
       @destroyed = true
-      @emit 'destroyed'
+      @emit 'destroyed', this
 
   isRetained: -> @refcount > 0