Reduce bundle size (#312)

## Before

```
Build "@projectwallace/css-analyzer" to dist:
      6.12 kB: analyzer.cjs.gz
       5.5 kB: analyzer.cjs.br
      5.61 kB: analyzer.modern.js.gz
      5.07 kB: analyzer.modern.js.br
      6.09 kB: analyzer.module.js.gz
      5.47 kB: analyzer.module.js.br
      6.22 kB: analyzer.umd.js.gz
      5.58 kB: analyzer.umd.js.br
```

## After

```
Build "@projectwallace/css-analyzer" to dist:
         6 kB: analyzer.cjs.gz
      5.38 kB: analyzer.cjs.br
      5.47 kB: analyzer.modern.js.gz
      4.93 kB: analyzer.modern.js.br
      5.97 kB: analyzer.module.js.gz
      5.38 kB: analyzer.module.js.br
       6.1 kB: analyzer.umd.js.gz
      5.47 kB: analyzer.umd.js.br
```

Author: bartveneman

src/string-utils.js

@@ -20,9 +20,10 @@ function compareChar(referenceCode, testCode) {
  * @returns {boolean} true if the two strings are the same, false otherwise
  */
 export function strEquals(base, test) {
-  if (base.length !== test.length) return false
+  let len = base.length;
+  if (len !== test.length) return false
 
-  for (let i = 0; i < base.length; i++) {
+  for (let i = 0; i < len; i++) {
     if (compareChar(base.charCodeAt(i), test.charCodeAt(i)) === false) {
       return false
     }
@@ -38,13 +39,14 @@ export function strEquals(base, test) {
  * @returns {boolean} true if `test` ends with `base`, false otherwise
  */
 export function endsWith(base, test) {
-  const offset = test.length - base.length
+  let len = test.length
+  const offset = len - base.length
 
   if (offset < 0) {
     return false
   }
 
-  for (let i = test.length - 1; i >= offset; i--) {
+  for (let i = len - 1; i >= offset; i--) {
     if (compareChar(base.charCodeAt(i - offset), test.charCodeAt(i)) === false) {
       return false
     }
@@ -60,7 +62,8 @@ export function endsWith(base, test) {
  * @returns {boolean} true if `test` starts with `base`, false otherwise
  */
 export function startsWith(base, test) {
-  if (test.length < base.length) return false
+  let len = base.length
+  if (test.length < len) return false
 
   for (let i = 0; i < base.length; i++) {
     if (compareChar(base.charCodeAt(i), test.charCodeAt(i)) === false) {

src/values/destructure-font-shorthand.js

@@ -34,38 +34,13 @@ const SIZE_KEYWORDS = new Set([
 	'larger',
 ])
 
-const STRETCH_KEYWORDS = new Set([
-	'ultra-condensed',
-	'extra-condensed',
-	'condensed',
-	'semi-condensed',
-	'semi-expanded',
-	'expanded',
-	'extra-expanded',
-	'ultra-expanded',
-])
-const STYLE_KEYWORDS = new Set(['italic', 'oblique'])
-const WEIGHT_KEYWORDS = new Set(['light', 'bold', 'bolder'])
-const VARIANT_KEYWORDS = new Set([
-	'small-caps',
-	'all-small-caps',
-	'petite-caps',
-	'all-petite-caps',
-	'unicase',
-	'titling-caps',
-])
-
 const COMMA = 44 // ','.charCodeAt(0) === 44
 const SLASH = 47 // '/'.charCodeAt(0) === 47
 
 export function destructure(value, stringifyNode) {
 	let font_family = []
 	let font_size
 	let line_height
-	let font_weight
-	let font_style
-	let font_variant
-	let font_stretch
 
 	value.children.forEach(function (node, item) {
 		// any node that comes before the '/' is the font-size
@@ -121,7 +96,6 @@ export function destructure(value, stringifyNode) {
 		// any node that's a number and not previously caught by line-height or font-size is the font-weight
 		// (oblique <angle> will not be caught here, because that's a Dimension, not a Number)
 		if (node.type == 'Number') {
-			font_weight = stringifyNode(node)
 			return
 		}
 
@@ -144,30 +118,10 @@ export function destructure(value, stringifyNode) {
 				font_size = node.name
 				return
 			}
-			if (STRETCH_KEYWORDS.has(node.name)) {
-				font_stretch = node.name
-				return
-			}
-			if (WEIGHT_KEYWORDS.has(node.name)) {
-				font_weight = node.name
-				return
-			}
-			if (STYLE_KEYWORDS.has(node.name)) {
-				font_style = node.name
-				return
-			}
-			if (VARIANT_KEYWORDS.has(node.name)) {
-				font_variant = node.name
-				return
-			}
 		}
 	})
 
 	return {
-		font_style,
-		font_variant,
-		font_weight,
-		font_stretch,
 		font_size,
 		line_height,
 		font_family: stringifyNode({