Revert "ConstantPoolSizeAt() should return number of Instructions instead, otherwise, some of the code will be treated as constant pool when printing code in ARM disassembler."

This reverts commit r16419 for breaking the ARM simulator tests.

TEST=mjsunit/regress/regress-2624
R=machenbach@chromium.org

Review URL: https://codereview.chromium.org/23531013

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@16441 ce2b1a6d-e550-0410-aec6-3dcde31c8c00