Minor performance optimizations

[821938089]

jsoup/src/main/java/org/jsoup/parser/HtmlTreeBuilder.java

Lines 393 to 395 in 2b443df

	// in HTML, the xmlns attribute if set must match what the parser set the tag's namespace to
	if (el.hasAttr("xmlns") && !el.attr("xmlns").equals(el.tag().namespace()))
	error("Invalid xmlns attribute [%s] on tag [%s]", el.attr("xmlns"), el.tagName());

el.hasAttr takes a bit of time to execute, which is unnecessary.

[jhy]

Cool, can you provide a PR and a benchmark?

[821938089]

I opened a PR.
#2099