Merge pull request #321 from bocoup/swallowed-assertions

test/built-ins/Function/prototype/S15.3.4_A5.js

test/built-ins/Function/prototype/toString/S15.3.4.2_A7.js

test/built-ins/Object/prototype/S15.2.4_A3.js

test/built-ins/Object/prototype/S15.2.4_A4.js

...built-ins/Object/prototype/hasOwnProperty/S15.2.4.5_A7.js

.../built-ins/Object/prototype/isPrototypeOf/S15.2.4.6_A7.js

...ins/Object/prototype/propertyIsEnumerable/S15.2.4.7_A7.js

...built-ins/Object/prototype/toLocaleString/S15.2.4.3_A7.js

test/built-ins/Object/prototype/toString/S15.2.4.2_A7.js

test/built-ins/Object/prototype/valueOf/S15.2.4.4_A7.js

test/built-ins/String/prototype/lastIndexOf/S15.5.4.8_A7.js

test/built-ins/String/prototype/slice/S15.5.4.13_A7.js

test/language/statements/block/S12.1_A2.js

test/language/statements/variable/S12.2_A1.js

test/language/statements/variable/S12.2_A5.js