Remove internal JS settings in favor of EmccOptions fields

[sbc100]

Remove internal settings OPT_LEVEL, USE_RTTI, DEBUG_LEVEL, EMIT_SYMBOL_MAP, SOURCE_MAP_BASE, and MINIFICATION_MAP from src/settings_internal.js and tools/settings.py since they are toolchain-internal settings not used in JavaScript libraries or runtime code. Store their state on EmccOptions fields instead.

[dschuff]

So the idea is that settings would only be for things that are needed in JS libraries?
I will say the distinction has so far been unclear to me, so this can make sense. maybe we could even rename it for clarity. Does Settings directly correspond to -s options on the command line?

[sbc100]

So the idea is that settings would only be for things that are needed in JS libraries? I will say the distinction has so far been unclear to me, so this can make sense.
maybe we could even rename it for clarity. Does Settings directly correspond to -s options on the command line?

Public settings do correspond to -s flags. For internal settings they cannot be set with -s flags but are set indirectly.

All public and internal settings get serialized to from python to the JS compiler and the JS compiler can use things like #if INTERNAL_SETTING. So my feeling is that we should avoid adding internal settings if/when we an just keep things internal to python. It saves a little bit of serializing cost and it avoids user JS libraries accidentally depending on internal things that we would prefer them not to depend on. i.e. normally we just assume that we can rename/delete internal settings at will, and we do, but technically user JS could be depending on them.

[dschuff]

Makes sense to me.