Add initial tests for trim(Start/End/Left/Right)

test/annexB/built-ins/String/prototype/trimLeft/length.js

test/annexB/built-ins/String/prototype/trimLeft/name.js

test/annexB/built-ins/String/prototype/trimLeft/prop-desc.js

test/annexB/built-ins/String/prototype/trimRight/length.js

test/annexB/built-ins/String/prototype/trimRight/name.js

.../annexB/built-ins/String/prototype/trimRight/prop-desc.js

test/built-ins/String/prototype/trimEnd/length.js

test/built-ins/String/prototype/trimEnd/name.js

test/built-ins/String/prototype/trimEnd/prop-desc.js

test/built-ins/String/prototype/trimStart/length.js

test/built-ins/String/prototype/trimStart/name.js

test/built-ins/String/prototype/trimStart/prop-desc.js