Add a specific error on compressed frames

[vbfox]

Instead of the generic 'invalid frame byte' a more specific error compressed frames aren't supported is returned when a compressed frame is received

Related to https://github.com/grpc/grpc-web/issues/561

[stanley-cheung]

@vbfox Sorry for the extreme delay. Just got around to run the tests and there was a syntax error

/github/grpc-web/packages/grpc-web/node_modules/.bin/google-closure-compiler --js=exports.js --js=../../javascript --js=../../third_party/closure-library --entry_point=grpc.web.Exports --externs=externs.js --dependency_mode=PRUNE --compilation_level=ADVANCED_OPTIMIZATIONS --generate_exports --export_local_property_definitions --js_output_file=index.js
../../javascript/net/grpc/web/grpcwebstreamparser.js:252: ERROR - [JSC_PARSE_ERROR] Parse error. '(' expected
const Parser = GrpcWebStreamParser;
      ^

1 error(s), 0 warning(s)
npm ERR! code ENOENT
npm ERR! syscall access
npm ERR! path /github/grpc-web/packages/grpc-web/node_modules/grpc-web.js
npm ERR! errno -2
npm ERR! enoent ENOENT: no such file or directory, access '/github/grpc-web/packages/grpc-web/node_modules/grpc-web.js'
npm ERR! enoent This is related to npm not being able to find a file.
npm ERR! enoent

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2020-12-05T01_20_58_770Z-debug.log
Service 'prereqs' failed to build: The command '/bin/sh -c cd ./packages/grpc-web &&   npm install &&   npm run build &&   npm link' returned a non-zero code: 254

Again my apologies for not getting to this.

[vbfox]

🤷🏼

[sampajano]

Apologies that these PRs slipped through the cracks during team transition.. If you think some of them are still valid and needed, please feel free to reopen.. sorry!