Fix various test issues

[anba]

test/annexB/built-ins/Date/prototype/setYear/time-clip.js
test/built-ins/Date/prototype/setFullYear/new-value-time-clip.js
test/built-ins/Date/prototype/setMonth/new-value-time-clip.js

• Don't try to test time-clip at the end points, because this is near
  impossible to get right (needs to consider time zone offset, dst, local
  mean time because of Africa/Monrovia, etc.).

test/built-ins/DataView/prototype/setFloat64/detached-buffer-after-toindex-byteoffset.js
test/built-ins/DataView/prototype/setInt16/detached-buffer-after-toindex-byteoffset.js

• Wasn't update to expect RangeError

test/built-ins/Function/internals/Construct/derived-this-uninitialized-realm.js

• Change ClassDeclaration -> ClassExpression to get completion value

test/built-ins/Function/prototype/toString/AsyncFunction.js

• Add missing \n in expected string

test/built-ins/global/global-object.js

• Add 'var' to make test pass in strict-mode

test/language/block-scope/syntax/redeclaration-in-block/attempt-to-redeclare-function-declaration-with-function-declaration.js

• This is allowed in sloppy mode when Annex B is implemented

test/language/expressions/async-generators/expression-yield-as-statement.js

• Fix calls to then()

test/language/module-code/namespace/internals/own-property-keys-binding-types.js
test/language/module-code/namespace/internals/own-property-keys-sort.js

• Tests weren't updated after removal of @@iterator from module
  namespace objects

test/language/module-code/namespace/internals/set-prototype-of-null.js

• Fix syntax error

test/language/statements/async-function/early-errors-no-async-generator.js

• No longer valid now that async iteration proposal is at stage 3

[anba]

Two fixes are now duplicated by #842 and #847.

[leobalter]

LGTM

[leobalter]

This is great! Thanks, @anba!

[littledan]

Thanks for this fix; I was about to report the second to last one.