Const not honored on string key in object literal

[ChadKillingsworth]

The @const annotation on an object literal key causes nested property types to fail to be recognized in NTI:

https://closure-compiler-debugger.appspot.com/#input0%3Dconst%2520module%2524foo%2520%253D%2520%257B%2520%252F**%2520%2540const%2520*%252F%2520prop%253A%2520%257B%257D%257D%253B%250A%252F**%2520%2540const%2520*%252F%2520module%2524foo.prop.Bar%2520%253D%2520class%2520%257B%257D%250A%250A%252F**%2520%2540param%2520%257Bmodule%2524foo.prop.Bar%257D%2520bar%2520*%252F%250Afunction%2520foobar(bar)%2520%257B%257D%26input1%26conformanceConfig%26externs%26refasterjs-template%26includeDefaultExterns%3Dtrue%26CHECK_SYMBOLS%3Dtrue%26MISSING_PROPERTIES%3Dtrue%26TRANSPILE%3Dtrue%26CHECK_TYPES_NEW_INFERENCE%3Dtrue%26CLOSURE_PASS%3Dtrue%26PRESERVE_TYPE_ANNOTATIONS%3Dtrue%26PRETTY_PRINT%3Dtrue