Typescript to 2.3 for now, to avoid build issues
Typescript to 2.3 for now, to avoid build issues

Typescript 2.4+ uncovered new issues that should be resolved. However temporarily staying at 2.3 gets Travis back to building, giving us some more breathing room to fix the new issues.

micmro/PerfCascade,micmro/PerfCascade,micmro/PerfCascade,micmro/PerfCascade