Speculative windows fix after 5aa6dbdccf1950daf0cd3014bf763f35899bccf9

Compile error is:

FAILED: E:/b/depot_tools/python276_bin/python.exe gyp-win-tool link-wrapper environment.x64 False link.exe /nologo /OUT:external_application_unittests.exe /PDB:external_application_unittests.exe.pdb @external_application_unittests.exe.rsp
application.application_impl.obj : error LNK2019: unresolved external symbol "public: static void __cdecl mojo::ApplicationImpl::Terminate(void)" (?Terminate@ApplicationImpl@mojo@@SAXXZ) referenced in function "private: void __cdecl mojo::ApplicationImpl::OnShellError(void)" (?OnShellError@ApplicationImpl@mojo@@AEAAXXZ)

external_application_unittests.exe : fatal error LNK1120: 1 unresolved externals

I suspect this is because //mojo/shell:external_application_unittests is
not declaring a dependency on //mojo/application, so it's not linking in
the chromium implementations of the mojo::ApplicationImpl lifetime methods.

It's not clear to me why this patch changed things and not
a600ca5310a2b0766dd9b000abd058520caf9fdf

TBR=jam@chromium.org

Review URL: https://codereview.chromium.org/754483002