Fix scroll position restoration

[chasenlehara]

Scroll position restoration is buggy in different browsers.

Here’s the code. I think most of it is unnecessary. https://github.com/canjs/bit-docs-html-canjs/blob/master/static/canjs.js#L334-L362

Below are a few common cases that we should get right. It’d be nice to have tests around these, similar to what we have for the sidebar:

bit-docs-html-canjs/sidebar/test.js

Lines 302 to 334 in 9eefe6a

	QUnit.test('Sidebar scrolls to selected items', function(assert) {
	var done = assert.async(1);
	var timeout = 20000;
	var timeoutID = setTimeout(function() {
	assert.notOk(true, 'Test took longer than ' + timeout + 'ms; test timed out.');
	}, timeout);
	// Open the demo page in an iframe
	FuncUnit.open('../sidebar/demo.html', function() {
	// Set the height & width of FuncUnit’s iframe
	FuncUnit.frame.height = 200;
	FuncUnit.frame.width = 600;
	// Select the can-ajax page
	FuncUnit('.go-to-can-ajax').click();
	// Check to make sure the element is visible
	FuncUnit('[selected-in-sidebar]').wait(function() {
	var element = this[0];
	if (!element) {
	return false;
	}
	var rect = element.getBoundingClientRect();
	return utils.rectIntersectsWithWindow(rect, FuncUnit.win);
	}, function() {
	clearTimeout(timeoutID);
	assert.ok(true, 'did scroll to selected element');
	done();
	});
	});
	});

1. Scroll down and refresh the page

It’s completely broken in Firefox:

2. Click on a specific section

When the user clicks on an in-page navigation link, the header for that section should be visible under the sticky header.

3. Refresh after going to a specific section

It lands on the wrong position in multiple browsers; here’s Firefox:

4. Refresh after going to a specific section and scrolling

After refreshing, the user should end up where they scrolled, not back at the old section. I think this is broken in all browsers.