Remove more IE compatibility

src/ol/format/GMLBase.js

@@ -36,16 +36,12 @@ export const GMLNS = 'http://www.opengis.net/gml';
 
 /**
  * A regular expression that matches if a string only contains whitespace
- * characters. It will e.g. match `''`, `' '`, `'\n'` etc. The non-breaking
- * space (0xa0) is explicitly included as IE doesn't include it in its
- * definition of `\s`.
- *
- * Information from `goog.string.isEmptyOrWhitespace`: https://github.com/google/closure-library/blob/e877b1e/closure/goog/string/string.js#L156-L160
+ * characters. It will e.g. match `''`, `' '`, `'\n'` etc.
  *
  * @const
  * @type {RegExp}
  */
-const ONLY_WHITESPACE_RE = /^[\s\xa0]*$/;
+const ONLY_WHITESPACE_RE = /^\s*$/;
 
 /**
  * @typedef {Object} Options

src/ol/format/KML.js

@@ -419,9 +419,6 @@ function defaultIconUrlFunction(href) {
  * geometry types, and into MultiPoint/MultiLineString/MultiPolygon if they are
  * all of the same type.
  *
- * Note that the KML format uses the URL() constructor. Older browsers such as IE
- * which do not support this will need a URL polyfill to be loaded before use.
- *
  * @api
  */
 class KML extends XMLFeature {

src/ol/format/readme.md

@@ -23,7 +23,6 @@ The document ends with guidelines for implementing a new format.
 
 The `ol/xml` namespace contains a number of useful functions for parsing XML documents. All code in OpenLayers that reads data from XML documents should use it. It has several features:
 
-* Browser support back to IE9
 * Correct treatment of XML namespaces
 * Robust handling of errors
 * Modular design to promote the re-use of parsers
@@ -42,7 +41,7 @@ The `ol/format/XML` class includes a number of methods for reading arrays of fea
 
     read{Features,Feature,Geometry}From{Document,Node}
 
-`Document`s are top-level XML document objects, `Node`s are children of the top-level XML document object. In modern browsers `Document` is a subclass of `Node`, and inherits all of `Node`'s methods.  In IE, this is not the case: `Document` is not a subclass of `Node`, and `Document` only has some of `Node`'s functionality.  The distinction between the two is therefore necessary.
+`Document`s are top-level XML document objects, `Node`s are children of the top-level XML document object. In modern browsers `Document` is a subclass of `Node`, and inherits all of `Node`'s methods.
 
 ## `ol/xml`