fixed iframe div

[dzy321]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Deprecations?	no
New tests added?	not needed
Fixed tickets	comma-separated list of tickets fixed by the PR, if any
License	MIT

Description

//content in iframe
var doc = content.ownerDocument;
var editor = new MediumEditor(content, {
      .........
      contentWindow: doc.defaultView || doc.parentWindow,
      ownerDocument: doc
});

if convert iframe's div to editor,it will throw error.

[coveralls]

Changes Unknown when pulling 59e2aa6 on dzy321:master into * on yabwe:master*.

[coveralls]

Changes Unknown when pulling ba4ea63 on dzy321:master into * on yabwe:master*.

[nmielnik]

@dzy321 thanks for finding and fixing this bug!

Can you remove the files from the /dist folder from this PR? (See the Contribution Guide)

Also, can you remove the changes from Gruntfile.js and package.json? I'm not sure what those changes are, but I don't think we want them in the core repo.

If possible, you may want to squash all of these into a single commit as well.

Thanks again! Once you fix up this PR, we'll be happy to merge this in.

[coveralls]

Changes Unknown when pulling 87c7f46 on dzy321:master into * on yabwe:master*.

[dzy321]

Thanks for you suggestion , i have recommited my pr.