Fix dynamic static calls on object targets

[yavon007]

Summary

• keep the stable-object fast path only for statically named methods
• route dynamic method names through the runtime object class and method value
• add code-generation and PHPT coverage for base/subclass object targets and named arguments

Testing

• vendor/bin/phpunit phpunit/src/CallCacheCodegenTest.php
• php run-tests.php -q --compiler ./tpc tests/compiler/static/static-call-dynamic-object-method.phpt tests/compiler/static/static-call-dynamic-method.phpt tests/compiler/dynamic_call/call-cache-dispatch.phpt