Web Inspector: make inspector protocol validation a part of the build process.

Web Inspector: make inspector protocol validation a part of the build process.
https://bugs.webkit.org/show_bug.cgi?id=68999

Since we'd like to commit to inspector protocol backwards compatibility, violating it
should be a build failure.

Reviewed by Yury Semikhatsky.

* CMakeLists.txt:
* CodeGenerators.pri:
* DerivedSources.make:
* GNUmakefile.am:
* WebCore.gyp/WebCore.gyp:
* inspector/Inspector.draft-01.json:
* inspector/Inspector.json:
* inspector/generate-inspector-idl:
* inspector/generate-protocol-externs:
* inspector/validate-protocol-compatibility:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@96320 268f45cc-cd09-0410-ab3c-d52691b4dbfc