Revert "[dart:html] Add 'creates' type description to JS calls"

This reverts commit 1a6420b.

Reason for revert: This changes signatures of public methods to return
private types (e.g. `Future<_Cache> open` in `CacheStorage` and
`Future<_Response> fetch` in `Window`), which is a breaking change
without any workaround and it breaks some mocks in customer code.

Original change's description:
> [dart:html] Add 'creates' type description to JS calls
>
> Closes #43225
>
> JS calls on promises need to include a type description for types
> that may be newly live after the call. Since type parameters in a
> promise are not parsed, type dictionary for these APIs is updated
> to include any possible types created and code gen is changed to
> include them in the JS foreign function call.
>
> Change-Id: I8c977e4b33b383093e4091f1be94199b342521b6
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/160781
> Reviewed-by: Stephen Adams <sra@google.com>
> Commit-Queue: Srujan Gaddam <srujzs@google.com>

TBR=sra@google.com,sigmund@google.com,srujzs@google.com

Change-Id: I345053f599457eccfed0efdf68cdea4179693362
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/161484
Reviewed-by: Ivan Inozemtsev <iinozemtsev@google.com>
Reviewed-by: David Morgan <davidmorgan@google.com>
Commit-Queue: David Morgan <davidmorgan@google.com>
Auto-Submit: Ivan Inozemtsev <iinozemtsev@google.com>

Author: iinozemtsev