Our existing `SubtleCrypto::normalize_algorithm` implementation converts
the input dictionary from a JavaScript object to a Rust struct twice.
The first conversion (Step 2 to 4) under WebIDL dictionary `Algorithm`
is for retrieving the `name` property to determine the desired
dictionary type, and the second conversion (Step 9 to 10) is for
retrieving the whole dictionary of desired WebIDL dictionary type.

If the `name` property of the input dictionary is a JavaScript getter
method, the getter will be triggered twice and leads to some undesired
side effects. For example, WPT contains some tests that the `name`
property is a getter method which transfers a buffer source. Triggering
it twice leads to a TypeError of accessing detached buffer at the second
time. Those tests then fail.


https://github.com/servo/servo/blob/5bb4f9f103e629fe38ea28bc67a8543a00cc6e60/tests/wpt/tests/WebCryptoAPI/digest/cshake.tentative.https.any.js#L215-L219

This patch includes two changes to fix this problem.

First, the algorithm name retrieved in Step 2 to 4 is now passed to
`Op::RegisteredAlgorithm::from_object` in Step 9 to 10 so that we don't
need to read the `name` property and trigger the getter method again.

Second, we no longer use `dictionary_from_jsval` for converting the
dictionary, since it reads the whole dictionary including the `name`
property, triggering the getter method again. Instead, we add some
custom helper functions (`get_optional_parameter`,
`get_required_parameter`, `get_optional_parameter_in_box`,
`get_required_parameter_in_box`, `get_optional_buffer_source`,
`get_required_buffer_source`) to manually read properties other the
`name` property one by one, in a way that matches the specification.

Hence, each property of the input dictionary will only be read once, to
avoid this issue.

Testing: Pass some WPT tests that were expected to fail.

---------

Signed-off-by: Kingsley Yung <kingsley@kkoyung.dev>