rrdom (#613)

* create rrdom package

* test(rrdom): add unit tests for polyfill.ts

* fix(rrweb snapshot): type check errors

Errors are caused by the declaration similarity of @types/mocha and @types/jest if we install both of them in the whole project.

* Set tagNames to upper case by default

This mirrors the `Element.tagName` implementation:

```
For DOM trees which represent HTML documents, the returned tag name is always in the canonical upper-case form. For example, tagName called on a <div> element returns "DIV".
```
https://developer.mozilla.org/en-US/docs/Web/API/Element/tagName

* Add workspace file

* VSCode settings for rrdom tests

* Add basic test for RRDocument

* Only setup jest tests for rrdom

* mock Node type and Event type for nodejs environment

* test(rrdom): add snapshot for document.test.ts

* fix issue of nwsapi import and add unit tests for rrdom

* fix: querySelectorAll returns nothing when querying elements with ids and classNames

* fix: error of unit test for Event polyfill

Since Event class is built in nodejs after v15.0.0

* add a dummy implementation of canvas

* add style element support

* add unit test for style element

Co-authored-by: Justin Halsall <Juice10@users.noreply.github.com>

packages/rrdom/src/style.ts

@@ -0,0 +1,40 @@
+export function parseCSSText(cssText: string): Record<string, string> {
+	const res: Record<string, string> = {};
+	const listDelimiter = /;(?![^(]*\))/g;
+	const propertyDelimiter = /:(.+)/;
+	cssText.split(listDelimiter).forEach(function (item) {
+	  if (item) {
+		const tmp = item.split(propertyDelimiter);
+		tmp.length > 1 && (res[camelize(tmp[0].trim())] = tmp[1].trim());
+	  }
+	});
+	return res;
+  }
+  
+  export function toCSSText(style: Record<string, string>): string {
+	const properties = [];
+	for (let name in style) {
+	  const value = style[name];
+	  if (typeof value !== 'string') continue;
+	  const normalizedName = hyphenate(name);
+	  properties.push(`${normalizedName}:${value};`);
+	}
+	return properties.join(' ');
+  }
+  
+  /**
+   * Camelize a hyphen-delimited string.
+   */
+  const camelizeRE = /-(\w)/g;
+  export const camelize = (str: string): string => {
+	return str.replace(camelizeRE, (_, c) => (c ? c.toUpperCase() : ''));
+  };
+  
+  /**
+   * Hyphenate a camelCase string.
+   */
+  const hyphenateRE = /\B([A-Z])/g;
+  export const hyphenate = (str: string): string => {
+	return str.replace(hyphenateRE, '-$1').toLowerCase();
+  };
+