Use dart compile wasm for wasm compilations

[mkustermann]

• Flags to dart compile wasm

  Some options are not relevant to a standalone user of dart compile wasm (e.g. specyfing dart-sdk, platform file etc). => Those aren't offered by the dart compile wasm tool directly. => We use the --extra-compiler-option= instead which passes through arbitrary options to the dart2wasm compiler. => We don't maintain compatibility of those options, if we update them we'll ensure to also update flutter tools

• Binaryen optimization passes

  This change will mean we use the binaryen flags from Dart SDK which are slightly different from the ones in flutter.

• Optimization configuration

  This change will also start using the more standardized -O flag for determining optimization levels. The meaning of those flags have been mostly aligned with dart2js (with some differences remaining).

• Minimization

  Using the new optimization flags, namely -O4 for --wasm-opt=full, will automatically enable the new --minify support. Minification is Dart semantics preserving but changes the <obj>.runtimeType.toString() to use minified names (just as in dart2js).

• Code size changes

  Overall this change will reduce wonderous code size by around 10%.

Issue dart-lang/sdk#54675

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[kevmoo]

LGTM, but @eyebrowsoffire should review, too

[eyebrowsoffire]

Looks good to me! Eventually I will probably want to get rid of the --omit-type-checks flag and just expose the -O level of the wasm compiler. I assume though that the only differences between -O2 and -O4 at the moment are the type checking?

[mkustermann]

Looks good to me! Eventually I will probably want to get rid of the --omit-type-checks flag and just expose the -O level of the wasm compiler.

Yes please :-)

We should align flutter's uses of dart2wasm and dart2js, to also ensure we get fair comparison numbers.

I assume though that the only differences between -O2 and -O4 at the moment are the type checking?

Flutter should simply use the same -O flags for dart2js and dart2wasm and the Dart compiler folks should ensure the optimization levels behaviors are aligned. -O2 is semantics preserving and starting at -O3 we stop following dart semantics.

Yes, right now the difference is type checks, but we may do more alignment between dart2js and dart2wasm in behavior of those flags.