Inserting inline macros in a page disrupts flow

Issue Summary

Inline macros are meant to be sized and displayed such that the flow of the page is uninterrupted, however, the sizing of app iframes to macro content is not working.

Steps to Reproduce

1. Install the test app using the descriptor URL https://dugaldmorrow.github.io/inlinedynamiccontentmacro/descriptor.json.
2. Insert the macro "Test Inline Dynamic Content Macro" in any page in line with any other inline content.
3. Check the macro's iframe is sized according to the content and displayed in line with the other page content.

Expected Results

The macro is sized according to the macro's content.

Actual Results

The macro's iframe is significantly wider than it's contents, resulting in a large gap between the macro content and the next inline content.

Workaround

The app must compute and resize (AP.resize(200, 20)) the content dynamically which may not always be feasible.