Setting kMinimumCodeRangeSize as 3*pagesize. This will set the
constant correctly for PPC where pagesize is 4MB.

R=mlippautz@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2206583004
Cr-Commit-Position: refs/heads/master@{#38450}