IDLs in core have 'implements' statements that depend on interfaces in modules, i.e.:
CoreFoo implements ModulesBar;

To avoid layer violation, these statements are moved to the implemented (RHS) IDL files.
The code generator is updated to support this.

BUG=358074
BUG=360435

Review URL: https://codereview.chromium.org/270573005

git-svn-id: svn://svn.chromium.org/blink/trunk@173599 bbb929c8-8fbe-4397-9dbb-9b2b20218538