Verify that callers correctly set parentUsesSize if they use the child's size (and fix a few cases that didn't). This introduces a bunch of code that should only run in debug builds, but we don't have #ifdefs yet.
Verify that callers correctly set parentUsesSize if they use the child's size (and fix a few cases that didn't).
This introduces a bunch of code that should only run in debug builds, but we don't have #ifdefs yet.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1182933003.

flutter/flutter,flutter/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,jason-simmons/flutter,cbracken/flutter,aghassemi/flutter,tvolkert/flutter,flutter/flutter,turnidge/flutter,Hixie/flutter,turnidge/flutter,Hixie/flutter,flutter/flutter,jason-simmons/flutter,Hixie/flutter,aghassemi/flutter,jason-simmons/flutter,Hixie/flutter,aghassemi/flutter,cbracken/flutter,flutter/flutter,cbracken/flutter,cbracken/flutter,turnidge/flutter,tvolkert/flutter,cbracken/flutter,jason-simmons/flutter,tvolkert/flutter,flutter/flutter,flutter/flutter,Hixie/flutter,aghassemi/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,turnidge/flutter,Hixie/flutter,cbracken/flutter,tvolkert/flutter,Hixie/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,Hixie/flutter,tvolkert/flutter,turnidge/flutter,flutter/flutter,cbracken/flutter