The GraphAssemblerLabel VarCount template parameter now can have a
marker value ~0 which is marker for it being dynamic sized -- this means
that a bit of template magic turns its std::arrays into std::vectors.
Merging GraphAssemblerLabels works by duck-typing access to these
arrays/vectors.

These dynamic GraphAssemblerLabels are created whenever a single

GraphAssemblerLabels being created when instead a list of values
convertible to MachineRepresentation is passed in. Passing anything else
will result in a GraphAssemblerLabel with marker value ~1, which is
considered "invalid" and will give a compilation error down the line.

std: :vector is passed into MakeLabel, with the static
Change-Id: I833bdedac2f8e26fcc88aa59dd67b7e4b1c4296d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3913349
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83424}