Within an inline stack we would have multiple copies of the exact same
CodeEntry object to represent an inline frame. We had one copy for every
time that the frame appeared in an inline stack. One CodeEntry can have
multiple inline stacks and each stack can have multiple inline frames.
In the common case, the stacks overlap and repeat frames.

This CL creates a single CodeEntry object to represent each inlined
function as an inline frame (for a given CodeEntry with inlinings). This
removes most of the duplication of inline CodeEntry objects. We still
have some duplication, e.g. if we inline bar() into foo() and foo2() but
they are not themselves inlined into anything, then we will have two
inline CodeEntry objects for bar(). Removing all duplication is harder
to achieve because the lifetime of the inlined frame CodeEntry is now no
longer tied to the inliner.

Get rid of the InlineEntry struct as it is now indentical to
CodeEntryAndLineNumber.

We store the list of canonical inline CodeEntry objects on the
CodeObject of the inlining function so that it can own the lifetimes of
inlined frames.

Also rename inline_locations_ to inline_stacks_ to be clearer.

Bug: v8:7719

Change-Id: Ied765b4cce7fd33f3290798331f1e6767cc42e8c
Reviewed-on: https://chromium-review.googlesource.com/c/1396086
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58639}