Changes 'is' checks for JS types such that it no longer does an
instance of check and instead only checks to see if the object
in question is a JS object or appropriate subtype. This means that
any two @JS objects will pass an is check and therefore can be
casted as one another. This makes it consistent with expected
behavior and dart2js.
Also amends the README to reflect the unified behavior.
Change-Id: I11aa105d6cafbbafde482b27dcc1182c0960cce9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/173140
Reviewed-by: Nicholas Shahan <nshahan@google.com>
Commit-Queue: Srujan Gaddam <srujzs@google.com>
Srujan Gaddam
8e663541c9