buffer: port `byteLengthUtf8` to JavaScript
Please don't land this PR yet. There is a missing V8 optimization, that is going to be available soon in V8 6.6.
Prior to this change the majority of the time spent when
calling Buffer.byteLength
was spent on crossing JS->C++ boundary. This
change move the function to JavaScript, making it much faster.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines
Affected core subsystem(s)
buffer