Merge pull request #356 from anba/regexp-cleanup

test/built-ins/RegExp/15.10.2.15-3-1.js

test/built-ins/RegExp/15.10.2.15-3-2.js

test/built-ins/RegExp/15.10.2.15-6-1.js

test/built-ins/RegExp/15.10.2.2-1.js

test/built-ins/RegExp/15.10.2.5-3-1.js

test/built-ins/RegExp/15.10.4.1-1.js

test/built-ins/RegExp/15.10.4.1-2.js

test/built-ins/RegExp/15.10.4.1-3.js

test/built-ins/RegExp/15.10.4.1-4.js

test/built-ins/RegExp/S15.10.2.15_A1_T1.js

test/built-ins/RegExp/S15.10.2.15_A1_T10.js

test/built-ins/RegExp/S15.10.2.15_A1_T11.js

test/built-ins/RegExp/S15.10.2.15_A1_T12.js

test/built-ins/RegExp/S15.10.2.15_A1_T13.js

test/built-ins/RegExp/S15.10.2.15_A1_T14.js

test/built-ins/RegExp/S15.10.2.15_A1_T15.js

test/built-ins/RegExp/S15.10.2.15_A1_T16.js

test/built-ins/RegExp/S15.10.2.15_A1_T17.js

test/built-ins/RegExp/S15.10.2.15_A1_T18.js

test/built-ins/RegExp/S15.10.2.15_A1_T19.js