Skip JSTests/microbenchmarks/string-index-of-* tests on memory limited platforms, as they are too slow.
Pull request: https://github.com/WebKit/WebKit/pull/2664
Test gardening commit 252740@main (092abab148b5): <https://commits.webkit.org/252740@main> Reviewed commits have been landed. Closing PR #2664 and removing active labels.
<rdar://problem/97461033>