DevTools is an order-of-magnitude too big

```
sdk$ du -sh out/ReleaseX64/dart-sdk/bin/resources/devtools/
90M out/ReleaseX64/dart-sdk/bin/resources/devtools/
```

90M is *way* too much relative to the complexity of DevTool's feature set. It should more more like 3-4MB.

```
sdk$ du -sh out/ReleaseX64/gen/runtime/observatory/observatory_archive.tar
3.8M out/ReleaseX64/gen/runtime/observatory/observatory_archive.tar
```

For comparison, Observatory, which has a feature set of roughly the same complexity, is more than an order-of-magnitude smaller, and Observatory itself should be at least a MB smaller if not for all the compatibility cruft handling when Polymer and Custom Elements were broken.

```
hopscotch$ du -ch out/*.wasm out/*.js out/*.webp out/HopscotchIDE.vfuel
...
3.0M total
```

For comparison, Hopscotch, with a slightly smaller feature set but containing its own tests, source code and a compiler, is only 3MB.

This looks like a good opportunity for DevTools to dogfood its own size analysis tools.