WebIDL codegen: Replace cmake with a single Python script

When playing around with Cargo’s new timing visualization:
https://internals.rust-lang.org/t/exploring-crate-graph-build-times-with-cargo-build-ztimings/10975/21

… I was surprised to see the `script` crate’s build script take 76 seconds.
I did not expect WebIDL bindings generation to be *that* computationally
intensive.

It turns out almost all of this time is overhead. The build script uses CMake
to generate bindings for each WebIDL file in parallel, but that causes a lot
of work to be repeated 366 times:

* Starting up a Python VM
* Importing (parts of) the Python standard library
* Importing ~16k lines of our Python code
* Recompiling the latter to bytecode, since we used `python -B` to disable
  writing `.pyc` file
* Deserializing with `cPickle` and recreating in memory the results
  of parsing all WebIDL files

----

This commit remove the use of CMake and cPickle for the `script` crate.
Instead, all WebIDL bindings generation is done sequentially
in a single Python process. This takes 2 to 3 seconds.

1 files changed, 0 insertions, 54 deletions

diff --git a/components/script/dom/bindings/codegen/BindingGen.py b/components/script/dom/bindings/codegen/BindingGen.py
deleted file mode 100644
index 63cc68e46e5..00000000000
--- a/components/script/dom/bindings/codegen/BindingGen.py
+++ /dev/null
@@ -1,54 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at https://mozilla.org/MPL/2.0/.
-
-import sys
-import os
-sys.path.append(os.path.join(".", "parser"))
-sys.path.append(os.path.join(".", "ply"))
-import cPickle
-from Configuration import Configuration
-from CodegenRust import CGBindingRoot, replaceFileIfChanged
-
-
-def generate_binding_rs(config, outputprefix, webidlfile):
-    """
-    |config| Is the configuration object.
-    |outputprefix| is a prefix to use for the header guards and filename.
-    """
-
-    filename = outputprefix + ".rs"
-    module = CGBindingRoot(config, outputprefix, webidlfile).define()
-    if not module:
-        print "Skipping empty module: %s" % (filename)
-    elif replaceFileIfChanged(filename, module):
-        print "Generating binding implementation: %s" % (filename)
-
-
-def main():
-    # Parse arguments.
-    from optparse import OptionParser
-    usagestring = "usage: %prog configFile outputdir outputPrefix webIDLFile"
-    o = OptionParser(usage=usagestring)
-    (options, args) = o.parse_args()
-
-    if len(args) != 4:
-        o.error(usagestring)
-    configFile = os.path.normpath(args[0])
-    outputdir = args[1]
-    outputPrefix = args[2]
-    webIDLFile = os.path.normpath(args[3])
-
-    # Load the parsing results
-    resultsPath = os.path.join(outputdir, 'ParserResults.pkl')
-    with open(resultsPath, 'rb') as f:
-        parserData = cPickle.load(f)
-
-    # Create the configuration data.
-    config = Configuration(configFile, parserData)
-
-    # Generate the prototype classes.
-    generate_binding_rs(config, outputPrefix, webIDLFile)
-
-if __name__ == '__main__':
-    main()