Remove test that has been disabled since April 2013

StringOperatorsText.cpp tried to measure how many copies a string
concatenation does but has been disabled since April 2013 and was
ultimately broken September 2014. This patch removes it because it
uses a macro in a way that is incompatibile with jumbo.

Bug: 761475
Change-Id: If224b7a7dac8660b1f50c2814deffcd2d664c0fe
Reviewed-on: https://chromium-review.googlesource.com/718703
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#508704}
4 files changed