Error code for PING frame with wrong size - https://github.com/http2/http2-spec/issues/246

Moving over from github.

Gabor:
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Currently, there's two contradicting MUSTs for this.

Section 4.2::

Certain frame types, such as PING (see Section 6.7), impose
additional limits on the amount of payload data allowed.  Likewise,
additional size limits can be set by specific application uses (see
Section 9).

If a frame size exceeds any defined limit, or is too small to contain
mandatory frame data, the endpoint MUST send a FRAME_TOO_LARGE error.
Frame size errors in frames that affect connection-level state MUST
be treated as a connection error (Section 5.4.1).
Section 6.7:

Receipt of a PING frame with a length field value other than 8 MUST
be treated as a connection error (Section 5.4.1) of type
PROTOCOL_ERROR.
I propose to simply omit the second one, or just reference the former
section.
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See https://github.com/http2/http2-spec/issues/246 for the rest of the
discussion.