This functionality is useful for stubs that need to walk the stack. The new
machine operator, LoadParentFramePointer dosn't force the currently compiling
method to have a frame in contrast to LoadFramePointer. Instead, it adapts
accordingly when frame elision is possible, making efficient stack walks
possible without incurring a performance penalty for small stubs that can
benefit from frame elision.

R=bmeurer@chromium.org
LOG=N

Review URL: https://codereview.chromium.org/1695313002

Cr-Commit-Position: refs/heads/master@{#34014}