Port 08756826

Original Commit Message:

    Port 4b0f9c85

    Original Commit Message:

        Our {Vector} template provides both {start} and {begin} methods. They
        return exactly the same value. Since the {begin} method is needed for
        iteration, and is also what standard containers provide, this CL
        switches all uses of the {start} method to use {begin} instead.

        Patchset 1 was auto-generated by using this clang AST matcher:
            callExpr(
                callee(
                  cxxMethodDecl(
                    hasName("start"),
                    ofClass(hasName("v8::internal::Vector")))
                ),
                argumentCountIs(0))

        Patchset 2 was created by running clang-format. Patchset 3 then
        removes the now unused {Vector::start} method.

R=miladfar@ca.ibm.com, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: Ief052e7655ede161504cf058eddd81714e6e5929
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1590168
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61142}