I extracted following class member functions to map.cc
* Map
* NormalizedMapCache

Declaration of all above class are in map.h.

This patch makes compile time of objects.cc from 18.9s to 17.6s on Z840 Linux.
And map.cc takes 6.14s for compile.

Bug: v8:7629
Change-Id: Id1e45dff243ab3f5449c0a7e2a861fba0bc7abf6
Reviewed-on: https://chromium-review.googlesource.com/c/1447914
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59270}