Added notes to block-level function declaration

Just some notes clarifying that this feature was indeed discouraged in
ES5, in case people are confused by its inclusion in the ES6 table.
Fixed whitespace in HTML files
Fixes ES5 and non-standard pages in IE 8

The ES5 and non-standard pages should now work in IE 8 again.
(The ES6 page, puzzlingly, seems to make it freeze or crash. Oh well,
it's almost midnight.)

Fixes include:
* Fallback for hsl() colours
* "Show obsolete browsers" checkbox works again
* Fallback for opacity when selecting a column
* Tooltips work again (incorrectly uses String#trim and Array#forEach)
Fixed syntax error in Symbol.hasInstance test

Accidentally used "class" as an identifier.
Merge pull request #242 from webbedspace/hasinstance

Fixed a syntax error in Symbol.hasInstance test
Merge pull request #238 from webbedspace/blockfunction-note

Added notes to block-level function declaration
Merge pull request #235 from webbedspace/gh-pages

Fixes ES5 and non-standard pages in IE 8
ES6: Added tests for each Proxy handler

This adds tests for the Proxy get, set, has, deleteProperty,
getOwnPropertyDescriptor, defineProperty, getPrototypeOf,
setPrototypeOf, isExtensible, preventExtensions, enumerate, ownKeys,
apply and construct handlers.
EJS support is inferred from the source.

Also fixes a few other results for old Firefox versions.

Sorry that this diff looks terrible, but if you run `git diff
--minimal`, it more accurately reflects the changes.
Added missing property names to the Reflect test
Added a Proxy.revocable test
Updated Proxy tests to multi-line comment strings

NOTE: this commit only updates data-es6.js.
Checks for proxy handler arguments

Proxy handler functions' standard arguments are now checked a bit more
thoroughly in the tests.

Also added a note about a Firefox bug regarding proxy inheritance.