Adding Sinon extern for getCalls().
Adding Sinon extern for getCalls().

This is needed to be able to assert that a stub/spy was called X number of times.

See the 1.17.7 documentation which lists `spy.getCalls()` as an API: https://sinonjs.org/releases/v1.17.7/spies/

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=216775407

shantanusharma/closure-compiler,vobruba-martin/closure-compiler,Yannic/closure-compiler,Yannic/closure-compiler,monetate/closure-compiler,monetate/closure-compiler,nawawi/closure-compiler,vobruba-martin/closure-compiler,google/closure-compiler,shantanusharma/closure-compiler,ChadKillingsworth/closure-compiler,google/closure-compiler,vobruba-martin/closure-compiler,Yannic/closure-compiler,nawawi/closure-compiler,shantanusharma/closure-compiler,monetate/closure-compiler,nawawi/closure-compiler,Yannic/closure-compiler,vobruba-martin/closure-compiler,ChadKillingsworth/closure-compiler,ChadKillingsworth/closure-compiler,nawawi/closure-compiler,google/closure-compiler,ChadKillingsworth/closure-compiler,monetate/closure-compiler,google/closure-compiler,shantanusharma/closure-compiler