Fixes for bug 33390 (r=mccabe, sr=shaver)

- Optimize compile (parse+emit) operation to generate code for each top-level
  statement or function in turn, recycling JSParseNodes as we go for greatly
  reduced "long linear script" footprint.
- Fix O(n**2) growth problems in bytecode and srcnote generation.
- Add js_ParseTokenStream entry point to compiler, for tree-generation without
  code-generation.  Move JSOP_EVAL instruction selection from code-generator to
  parser, to match other such specializations and enable js_ParseTokenStream.
- Fix js_CompileTokenStream (and get it right in new js_ParseTokenStream) to
  respect JSOPTION_VAROBJFIX.
- Clean up bracing, multi-line conditions, and overlong lines.