[[Get]] method doesn't exist in CredMan

[emlun]

§5.1.4. Use an Existing Credential to Make an Assertion - PublicKeyCredential’s [[Get]](options) Method appears to reference a [[Get]] internal method on the Credential interface from CredMan, but no such internal method exists (unlike [[Create]], which does exist). Rather, [[DiscoverFromExternalSource]] is the actual internal method we override.

Proposed Change

• Delete the heading §5.1.4.1. PublicKeyCredential’s [[DiscoverFromExternalSource]](origin, options, sameOriginWithAncestors) Method (without changing any of the text around it).
• Rename the heading §5.1.4. Use an Existing Credential to Make an Assertion - PublicKeyCredential’s [[Get]](options) Method to 5.1.4. Use an Existing Credential to Make an Assertion - PublicKeyCredential’s [[DiscoverFromExternalSource]](origin, options, sameOriginWithAncestors) Internal Method.
• For consistency, change "Method" to "Internal Method" in the heading §5.1.3. Create a New Credential - PublicKeyCredential’s [[Create]](origin, options, sameOriginWithAncestors) Method.
• Similarly, change "Method" to "Internal Method" in the heading §5.1.5. Store an Existing Credential - PublicKeyCredential’s [[Store]](credential, sameOriginWithAncestors) Method.

[emlun]

The [[Get]] was added in commit 46d6c51 in PR #672. The reason appears to have been for consistency with §5.1.3. Create a New Credential - PublicKeyCredential’s [[Create]](origin, options, sameOriginWithAncestors) Method. "Use an existing credential to make an assertion" already had a "[[DiscoverFromExternalSource]]" sub-heading; the reason this was (and still is) a sub-heading appears to be because "Use an existing credential to make an assertion" refers to both [[DiscoverFromExternalSource]] and [[CollectFromCredentialStore]] and how they interact.

[emlun]

2024-10-02 WG call: hearing no objections to this. @emlun to open a PR.