Warn if main exists but is not exported (emscripten-core#9159)

As it may be dce'd, and then not run.

A possible reason this might happen is doing ./emcc -s EXPORTED_FUNCTIONS=["_myfunc"] and forgetting to also have _main (which it is by default, but the commandline flag overrode the default value).

Make read, readAsync, readBinary, setWindowTitle normal JS variables (e…

…mscripten-core#9047)

This replaces Module['readBinary'] with readBinary etc., that is, moves them from Module to be just normal JS variables.

This change allows better JS minification: the names read, readAsync etc. can be minified now, and even better if the variables are not used then they can be removed entirely. On hello world this saves 4% of JS size in -O3 --closure 1 with the wasm backend.

This is an internal API change. However, it's possible some users depend on it, so I added a mention in the changelog, and in builds with ASSERTIONS an error message is shown if the old APIs are used.

Note that read is also renamed to read_ (since "read" is an API call in the SpiderMonkey shell).

Fix browser harness logging (emscripten-core#8980)

Turns out at least some of the duplicate logging we have is because if a python web request hander doesn't return any headers, it just calls it again. Odd that this doesn't recurse infinitely... anyhow, just send some empty headers for the logging code to avoid that.

Also fix the logging in python3, where urllib is structured differently.

Add extended Node feature check to fix issue emscripten-core#8816 (em…

…scripten-core#8832)

Handle a tiny {} function body in modifyFunction, which can happen wh…

…en bysyncify adds extra assertion checks (emscripten-core#8855)

show an error on trying to use bysyncify with fastcomp (emscripten-co…

…re#8857)

update changelog

Use a response file if necessary in llvm opt invocation (emscripten-c…

…ore#8784)

On fastcomp we defer linking  and send potentially a long list of files into llvm opt.

Make tools/gen_struct_info.py runnable with no args (emscripten-core#…

…8716)

Also, make it pretty print by default.

This should allow for easier debugging.

Added parameterized test support and use it for metadce (emscripten-c…

…ore#8653)

This converts a single tests that do the same thing with different parameters
into multiple tests.

The advantages of doing this is that the tests can now run in parallel, and you
can get feedback for all the subtests at the same time, instead of stopping the
test after the first failure. You can also run the just one subtest, instead of
running all or nothing.

This commit also adds `@functools.wraps` to decorators in `runner.py`
to preserve function attributes after decorating them.