no, the closed source part can stay closed source but relinking against a custom version of Blink must be allowed.

Just run "strings" on the code binary: you'll see symbols coming straight from Blink like this one: https://github.com/chromium/chromium/blob/72ceeed2ebcd505b8d...

    $ strings code-insiders | grep HTMLFormControls
    HTMLFormControlsCollection

    $ objdump -p  /opt/visual-studio-code-insiders/code-insiders | grep NEEDED
     NEEDED               libffmpeg.so
     NEEDED               libdl.so.2
     NEEDED               libpthread.so.0
     NEEDED               librt.so.1
     NEEDED               libgobject-2.0.so.0
     NEEDED               libglib-2.0.so.0
     NEEDED               libxshmfence.so.1
     NEEDED               libgio-2.0.so.0
     NEEDED               libnss3.so
     NEEDED               libnssutil3.so
     NEEDED               libsmime3.so
     NEEDED               libnspr4.so
     NEEDED               libatk-1.0.so.0
     NEEDED               libatk-bridge-2.0.so.0
     NEEDED               libdbus-1.so.3
     NEEDED               libdrm.so.2
     NEEDED               libgdk_pixbuf-2.0.so.0
     NEEDED               libgtk-3.so.0
     NEEDED               libgdk-3.so.0
     NEEDED               libpango-1.0.so.0
     NEEDED               libcairo.so.2
     NEEDED               libm.so.6
     NEEDED               libX11.so.6
     NEEDED               libXcomposite.so.1
     NEEDED               libXdamage.so.1
     NEEDED               libXext.so.6
     NEEDED               libXfixes.so.3
     NEEDED               libXrandr.so.2
     NEEDED               libexpat.so.1
     NEEDED               libxcb.so.1
     NEEDED               libxkbcommon.so.0
     NEEDED               libgbm.so.1
     NEEDED               libasound.so.2
     NEEDED               libatspi.so.0
     NEEDED               libgcc_s.so.1
     NEEDED               libc.so.6
     NEEDED               ld-linux-x86-64.so.2