Server-side support was removed in 77a942b7fe,
but client-side support was retained as it appeared NSS supported this.
However, this is not the case: ssl3_HandleServerKeyExchange only allows a
ServerKeyExchange message if hs.ws is in an appropriate state.
ssl3_AuthCertificate only sets it to allow ServerKeyExchange if it is a key
exchange that normally uses it or if is_limited is set. is_limited is only set
for the export cipher suites.
Thus we can safely remove this without waiting on gathering UMA data.
BUG=chromium:400587
Change-Id: I9aefb742dbb2d99c13340ab48017e1ceee04bc2f
Reviewed-on: https://boringssl-review.googlesource.com/2230
Reviewed-by: Adam Langley <agl@google.com>
525a0fe315