[fix] binding member expression should only invalidate the object, not the member property

[tanhauhau]

Fixes #6921

Previously when binding a member expression a[b][c], Svelte will invalidate all a, b, c whenever the bound value changes.

with the fix, Svelte will only invalidate a.

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Tests

• Run the tests with npm test and lint the project with npm run lint

[Conduitry]

@tanhauhau I've fixed the TypeScript issue so that the project can build and the tests run, but now a lot of tests seem to be failing.