RFR: 8296265: Use modern HTML in the JVMTI spec

[Alex Menkov]

Changes:
- removed `<b>` from TOC;
- added CSS style for TOC (to simplify customization, currently it's empty);
- removed `<b>` from from function list (per Phase);
- removed `<b>` from from list of events;
- introduced CSS style for bold text, replaced `<b>` tags with `<span class="bold">`;
- update transformation rule for `"b"` elements to use `"span class=bold"` (to handle `<b>` tags in source XML file);
- dropped duplicate `"b"` transform.

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Commit messages:
 - Fixed jvmti.xsl

Changes: https://git.openjdk.org/jdk/pull/11099/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11099&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296265
  Stats: 53 lines in 1 file changed: 2 ins; 16 del; 35 mod
  Patch: https://git.openjdk.org/jdk/pull/11099.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11099/head:pull/11099

PR: https://git.openjdk.org/jdk/pull/11099