Supersedes #113637/#116684. Branches off #118410.

Note for self: update #117228 and lower its priority after merge.

Context

When loading an asset for the first time, the framework has to load a file called the asset manifest, which contains information about assets available to the app (for example, where to find higher-resolution variants of images). This file is in the JSON format.

Reading the file from storage, decoding into UTF, and parsing it as JSON is generally slower than we'd like, especially since this is will all likely happen on first paint (since many apps include assets on their first screens).

#117233 updated the tool to also generate a binary-formatted version of the asset manifest. The binary-format enables faster loading and parsing of the file. This change utilizes this new asset manifest for resolving assets.

Here are the results from running the load_and_parse_large_asset_manifest benchmark on a Galaxy A02S before and after the change:

• Before: 9608ms, 9539ms, 9508ms (average 9551.7ms)
• After: 598ms, 422ms, 431ms (average 483.7ms)

In apps with large asset manifests, such as money (g3), running on lower-spec devices, this should hopefully result in a speed up of at least one frame when loading.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• All existing and new tests are passing.

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