Don't use trimRight since it isn't supported in IE

lib/line_wrapper.coffee

@@ -141,12 +141,12 @@ class LineWrapper extends EventEmitter
         lh = @document.currentLineHeight(true)
         if @height? and @ellipsis and @document.y + lh * 2 > @maxY and @column >= @columns
           @ellipsis = '…' if @ellipsis is true # map default ellipsis character
-          buffer = buffer.trimRight()
+          buffer = buffer.replace(/\s+$/, '')
           textWidth = @wordWidth buffer + @ellipsis
           
           # remove characters from the buffer until the ellipsis fits
           while textWidth > @lineWidth
-            buffer = buffer.slice(0, -1).trimRight()
+            buffer = buffer.slice(0, -1).replace(/\s+$/, '')
             textWidth = @wordWidth buffer + @ellipsis
         
           buffer = buffer + @ellipsis

lib/mixins/text.coffee

@@ -182,7 +182,7 @@ module.exports =
     if options.width
       switch align
         when 'right'
-          textWidth = @widthOfString text.trimRight(), options
+          textWidth = @widthOfString text.replace(/\s+$/, ''), options
           x += options.lineWidth - textWidth
 
         when 'center'