Improve the performance of Node.getQualifiedName
Improve the performance of Node.getQualifiedName

The way this was implemented recursively it would cause one StringBuilder to
be instantiated for each level of a qualified name so

a.b.c.d

would allocate 3 StringBuilders and the string 'a' would get copied 6 times.
(once into the string builder and once calling toString on the builder) With
this change we will allocate exactly one StringBuilder and copy 'a' exactly 2
times (no matter how many levels of qualification there are).  This should be
faster and produce much less garbage.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=139499722

anomaly/closure-compiler,tiobe/closure-compiler,Dominator008/closure-compiler,Pimm/closure-compiler,GerHobbelt/closure-compiler,MatrixFrog/closure-compiler,shantanusharma/closure-compiler,monetate/closure-compiler,anomaly/closure-compiler,monetate/closure-compiler,MatrixFrog/closure-compiler,vobruba-martin/closure-compiler,tiobe/closure-compiler,GerHobbelt/closure-compiler,monetate/closure-compiler,Yannic/closure-compiler,monetate/closure-compiler,anomaly/closure-compiler,ChadKillingsworth/closure-compiler,Yannic/closure-compiler,GerHobbelt/closure-compiler,vobruba-martin/closure-compiler,google/closure-compiler,ChadKillingsworth/closure-compiler,anomaly/closure-compiler,tdelmas/closure-compiler,Yannic/closure-compiler,Pimm/closure-compiler,google/closure-compiler,tdelmas/closure-compiler,nawawi/closure-compiler,shantanusharma/closure-compiler,GerHobbelt/closure-compiler,shantanusharma/closure-compiler,brad4d/closure-compiler,mprobst/closure-compiler,Dominator008/closure-compiler,Dominator008/closure-compiler,ChadKillingsworth/closure-compiler,MatrixFrog/closure-compiler,tiobe/closure-compiler,ChadKillingsworth/closure-compiler,tdelmas/closure-compiler,shantanusharma/closure-compiler,brad4d/closure-compiler,MatrixFrog/closure-compiler,brad4d/closure-compiler,mprobst/closure-compiler,tiobe/closure-compiler,google/closure-compiler,nawawi/closure-compiler,mprobst/closure-compiler,Yannic/closure-compiler,mprobst/closure-compiler,google/closure-compiler,Pimm/closure-compiler,tdelmas/closure-compiler,nawawi/closure-compiler,vobruba-martin/closure-compiler,nawawi/closure-compiler,vobruba-martin/closure-compiler