generate some type coercion tests

test/built-ins/BigInt/asIntN/bigint-tobigint-errors.js

test/built-ins/BigInt/asIntN/bigint-tobigint-toprimitive.js

...built-ins/BigInt/asIntN/bigint-tobigint-wrapped-values.js

test/built-ins/BigInt/asIntN/bigint-tobigint.js

test/built-ins/BigInt/asIntN/bits-toindex-errors.js

test/built-ins/BigInt/asIntN/bits-toindex-toprimitive.js

test/built-ins/BigInt/asIntN/bits-toindex-wrapped-values.js

test/built-ins/BigInt/asIntN/bits-toindex.js

test/built-ins/BigInt/asUintN/bigint-tobigint-errors.js

test/built-ins/BigInt/asUintN/bigint-tobigint-toprimitive.js

...uilt-ins/BigInt/asUintN/bigint-tobigint-wrapped-values.js

test/built-ins/BigInt/asUintN/bigint-tobigint.js

test/built-ins/BigInt/asUintN/bits-toindex-errors.js

test/built-ins/BigInt/asUintN/bits-toindex-toprimitive.js

test/built-ins/BigInt/asUintN/bits-toindex-wrapped-values.js

test/built-ins/BigInt/asUintN/bits-toindex.js

...ins/String/prototype/indexOf/position-tointeger-bigint.js

...ins/String/prototype/indexOf/position-tointeger-errors.js

...tring/prototype/indexOf/position-tointeger-toprimitive.js

...ng/prototype/indexOf/position-tointeger-wrapped-values.js