Minor tools/grokdump improvements: avoid some None dereferences and add some line breaks to generated html pages.
Minor tools/grokdump improvements: avoid some None dereferences and add some line breaks to generated html pages.

Review URL: https://codereview.chromium.org/943573002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#26752}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh