Make pdfium_embeddertests link in debug component builds.

Target v8 has:

          'direct_dependent_settings': {
            'defines': [

For this to work, targets using v8 headers have to depend on v8
directly, else the V8_EXPORT macro won't work. Add a direct
dependency on v8.

TEST=do a debug component build of pdfium_embeddertests on Win,
should work without linker errors

Review URL: .
2 files changed