The Closure Compiler is very picky with regard to JSDoc formatting. This
change fixes a few invalid JSDoc issues, and removes the corresponding
suppresses from the BUILD file. Additionally, modify the transpilation
target language to ES5.
After this change, there should no longer be warnings from the Closure
Compiler during building of PolyGerrit.
Change-Id: If7566e40c2c419c55f2a634c0f558c6cc263f61c