Add is_a? test to cover issue 1477
remove unnecessary keep size adjustment in stack_extend_alloc(); close #1602
Merge pull request #1604 from carsonmcdonald/1477isatest

Add is_a? test to cover issue 1477
Fix ISO no in Array#* and Array#+
Merge pull request #1605 from suzukaze/test-array

Fix ISO no in Array#* and Array#+
Fix mod.constants cannot return the single character constant
Merge pull request #1606 from bggd/patch-1

Fix mod.constants cannot return the single character constant
modify test case to check #1606
Avoid recursive instance variable inspections
Merge pull request #1607 from h2so5/avoid-recursive-inspection

Avoid recursive instance variable inspections
Fixed callinfo buffer overflow while calling ensure handlers
Merge pull request #1608 from nanamiwang/vmcrash

Fixed callinfo buffer overflow while calling ensure handlers