When reading an SWF, search for FileAttributes and
SetBackgroundColor and return this along with the header data
because it's useful (in particular, the AS3 flag).
If a textfield was created with a variable binding, and the variable
already existed, the initial text of the textfield is set to the
variable value. However, this was not obeying the HTML setting of
the text field, so HTML tags were mistakenly shown in some content.
Fixes#3522.
MovieClip.getBytesLoaded and getBytesTotal return the size of that
specific clip, even if it's not a loaded SWF. The previous logic
only returned the size of the parent SWF.
If the clip is an SWF, the uncompressed size of the SWF is returned.
Otherwise, the length of the tag list inside the clip's DefineSprite
tag is returned.
This allows `regressions_tests.rs` to depend on other crates in the
workspace, such as `render`, without introducing a cyclic dependency.
Split out from #4054