Directive isolate scope '=' with JSON in DOM causes $digest to reach max iterations. (But will parse the JSON)

[bobslaede]

Having a directive run on the following html, and trying to to get the JSON object from the attribute breaks.
<foo bar='{"foo":"bar"}'></foo>
The JSON is extracted, but it throws Uncaught Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!

Example bin: http://jsbin.com/UKOMuZi/13/edit

I'm not sure what should happen, either it shouldn't work, and then error, or it should keep working, but not throw an error.

[petebacondarwin]

Duplicate of #3980

[justinmc]

I'm getting this same problem in v1.2.3, even though the duplicate referenced says it's fixed. The workaround provided also seemed to not apply to this case...

[caitp]

This seems like it shouldn't be an issue, because the watcher should be unregistered if it determines the object is a constant. What's going on with that?

@petebacondarwin, looking at #3980, I'm not sure this actually was a duplicate. There's no filter in the reproduction, so the parser should tell us it's a constant and the watch should be unregistered.

However, this does appear to have been fixed a while ago, I don't feel like bisecting to find the specific commit, but it's been dealt with, probably 43072e3 (so @justinmc, you should be okay with 1.2.5 or higher)