Update postmortem metadata generation script

Update postmortem metadata constants for V8 7.8 in Node.js.

Change-Id: Ia2bf5ef611f4f6d87783b1fd1b340ae42e4a92a0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1849139
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64238}

tools/gen-postmortem-metadata.py

@@ -259,6 +259,8 @@ extras_accessors = [
     'JSArrayBuffer, byte_length, size_t, kByteLengthOffset',
     'JSArrayBufferView, byte_length, size_t, kByteLengthOffset',
     'JSArrayBufferView, byte_offset, size_t, kByteOffsetOffset',
+    'JSDate, value, Object, kValueOffset',
+    'JSRegExp, source, Object, kSourceOffset',
     'JSTypedArray, external_pointer, uintptr_t, kExternalPointerOffset',
     'JSTypedArray, length, Object, kLengthOffset',
     'Map, instance_size_in_words, char, kInstanceSizeInWordsOffset',