Don't make assumptions about the character width in specs

spec/atom/editor-spec.coffee

@@ -52,13 +52,13 @@ describe "Editor", ->
 
     describe "when soft-wrap is enabled", ->
       beforeEach ->
-        editor.width(11 * 50)
+        otherEditor = new Editor
+        otherEditor.attachToDom()
+        charWidth = otherEditor.charWidth
+        otherEditor.remove()
+        editor.width(charWidth * 50)
         editor.setSoftWrap(true)
         editor.attachToDom()
-        # this verifies the assumption made above in setting the editor's width
-        # charWidth isn't be calculated until it's the editor is on the DOM, but
-        # we need to ensure that the maxLineLength is recalculated when we attach.
-        expect(editor.charWidth).toBe 11
 
       it "wraps lines that are too long to fit within the editor's width, adjusting cursor positioning accordingly", ->
         expect(editor.lines.find('.line').length).toBe 16