stream: improve read() performance

Result:

                                                        confidence improvement accuracy (*)   (**)   (***)
 streams/readable-readall.js n=5000                           ***     85.06 %       ±2.87% ±3.84%  ±5.05%

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines