VM: Restore checking fingerprints of recognized methods

[alexmarkov]

VM used to check source fingerprints of 'recognized' methods in core libraries.

Condition in Function::CheckSourceFingerprint includes kernel_offset() <= 0 which is false since Dart 2. We need to restore these checks.

/cc @aartbik @mraleph @a-siva @rmacnak-google

I believe this (temporarily) invalidates the comment here:

sdk/runtime/vm/compiler/recognized_methods_list.h

Lines 12 to 13 in c5ea3e8

	// When adding a new function, add a 0 as the fingerprint and run the build in
	// debug mode to get the correct fingerprint from the mismatch error.

Since the code to generate the new fingerprints has been disabled:

sdk/runtime/vm/object.cc

Lines 9165 to 9170 in c5ea3e8

	#if 1
	// The non-nullable experiment changes the fingerprints, we only track
	// one fingerprint set, until we unfork and settle on a single snapshot
	// version this check has to be bypassed.
	// TODO(36376) - Restore checking fingerprints of recognized methods.
	#else

Unless there's some other mechanism I'm unaware of we should probably amend the first comment to clarify expectations.

[alexmarkov]

Fingerprints checking was disabled once again when we had 2 versions of core libraries (sdk and sdk_nnbd).
After SDK unforking we have only one version of core libraries, so we should re-enable fingerprints checking by removing this #if and updating all fingerprints.