Unskip serializer tests

These tests can be unskipped now that off-heap trampolines are packed
into the binary.

Bug: v8:6666
Change-Id: Ib8d55064a42da3b12fd940441298e5273181c601
Reviewed-on: https://chromium-review.googlesource.com/1047165Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53023}

test/cctest/cctest.status

@@ -131,16 +131,6 @@
   'test-serialize/CustomSnapshotDataBlobImmortalImmovableRoots': [PASS, ['mode == debug', SKIP]],
   'test-parsing/ObjectRestNegativeTestSlow': [PASS, ['mode == debug', SKIP]],
 
-  # Temporary for https://crrev.com/c/947969 until https://crrev.com/c/950775
-  # lands. Tests build a new snapshot, in which the constants list doesn't
-  # match what's expected by embedded builtins. This will become irrelevant
-  # once the serialization process changes to pack trampolines into the
-  # snapshot iff explicitly requested.
-  'test-serialize/StartupSerializerOnce': [SKIP],
-  'test-serialize/StartupSerializerTwice': [SKIP],
-  'test-serialize/StartupSerializerOnceRunScript': [SKIP],
-  'test-serialize/StartupSerializerTwiceRunScript': [SKIP],
-
   # Until https://crbug.com/v8/7718 is fixed.
   'test-serialize/PartialSerializerCustomContext': [SKIP],
 }],  # ALWAYS