Fix formatting of Profiling_js memory table
Fix formatting of Profiling_js memory table

Summary:
When you run Flow with `--profile` we print out tables of timing stats and memory stats. The memory stats table had a few small issues, which became apparent as I started to use it more later in this stack.

1. We'd print out empty sections
2. Whitespace was a little off
3. Percentages larger than `99.9` threw off the sizes.

Reviewed By: mroch

Differential Revision: D16209938

fbshipit-source-id: c9f800f018eccd3f6bd70eec69487110bcb39f22

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow