Request for reviews (S): 6809798: SafePointScalarObject node placed into incorrect block during GCM

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/6809798/webrev.00

Fixed 6809798: SafePointScalarObject node placed into incorrect block during GCM

Problem:
The main problem is that the control edge of a pinned node
could be replaced during schedule_early after the pinned
node scheduled into a block if the control node is a block
projection.
Also there were few places where the control edge of
a SafePointScalarObject node was not adjusted correctly.

Solution:
Replace the control edge of a pinned node before scheduling.
Adjust the control edge of a SafePointScalarObject when needed.
Added few asserts to verify scheduling correctness for
pinned nodes and SafePointScalarObject node.

Reviewed by:

Fix verified (y/n): y

Other testing:
JPRT, CTW (with -XX:+DoEscapeAnalysis)