Ported from TFS WorkItem: 1113197

Repro Steps:

1) Create a compilation analyzer (has a compilation start action which registers an end action + additional symbol/syntax node action)

2) Add the analyzer to a project and open the project in VS.

3) Add code to project to ensure symbol/syntax node fires

Expected: Symbol/syntax node action are never called multiple times for a given symbol/syntax node in a compilation

Actual: Multiple invocation can intermittently happen in IDE, current design doesn't guard against it.