Use root compiler instance for inline result and policy

Use root compiler instance for inline result and policy

When constructing an InlineResult (and subsequent InlinePolicy)
always use the root compiler instance, so that all policy evaluations
done in a method are consistent.

Add an assert that the initial fact replay during `fgFindJumpTargets`
(force inline state and code size) doesn't change the candidacy when
inlining -- it should just be re-establishing what we knew in the
initial candidate scan.

Closes #3760.