[dart2wasm] Reverted switch-case optimizations, seemingly introduced a bug

[mkustermann]

In 21f7ffc I reverted the switch-case optimizations (b654350, 2254755) which seemingly have introduced a bug.

With the dart2wasm self-compile test in the repo (patch in cl/442860) the issue can be reproduced by running

% tools/build.py -mrelease create_sdk

% python3 tools/test.py -n unittest-mac pkg/dart2wasm/test/self_compile_test
...
Exception in StaticInvocation at file:///FakeSdkRoot/sdk/lib/_internal/wasm/lib/boxed_double.dart:346:29
Bad state: Unhandled WasmArray intrinsic: StaticIntrinsic.wasmArrayIndex
    at module0.Error._throwWithCurrentStackTrace (wasm://wasm/module0-0121906a:wasm-function[160]:0xd0d76)
    at module0.AstCodeGenerator.visitStaticInvocation (checked entry) (wasm://wasm/module0-0121906a:wasm-function[6304]:0x1668e5)
    at module0._TreeVisitor1Default&Object&TreeVisitor1DefaultMixin&ExpressionVisitor1DefaultMixin.visitStaticInvocation (checked entry) (wasm://wasm/module0-0121906a:wasm-function[6306]:0x167b61)
    at module0.StaticInvocation.accept1 (wasm://wasm/module0-0121906a:wasm-function[6297]:0x165f5f)
    at module0.AstCodeGenerator.translateExpression (wasm://wasm/module0-0121906a:wasm-function[1742]:0xfcd1b)
    at module0.AstCodeGenerator.visitEqualsCall (checked entry) (wasm://wasm/module0-0121906a:wasm-function[6960]:0x1777e4)
    at module0.EqualsCall.accept1 (wasm://wasm/module0-0121906a:wasm-function[6944]:0x1773b4)
    at module0.AstCodeGenerator.translateExpression (wasm://wasm/module0-0121906a:wasm-function[1742]:0xfcd1b)
/Users/kustermann/src/dart-sdk/sdk/pkg/dart2wasm/bin/run_wasm.js:346: [object WebAssembly.Exception]

After reverting the switch-case optimizations (b654350, 2254755) this issue goes away, so I assume they are the cause of it.

@biggs0125 Maybe you can have a look?

[biggs0125]

Taking a look