tools: add no-misleading-character-class ESLint rule
Checklist
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make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
commit message follows commit guidelines
ESLint 5.3.0 adds a simple new rule that seems helpful for increasing Unicode support in JavaScript and Node.js: no-misleading-character-class
.
Since we have already updated to the last version, we can toggle this rule on.
No relevant issues detected in our code or docs.