Update testing packages

This updates Chai, Karma and Sinon. The breaking changes in Karma
6.0.0 don't affect us.

DISABLE_THIRD_PARTY_CHECK=NPM update
R=jacktfranklin@chromium.org

Bug: none
Change-Id: I77c2d4b1aeb1f0544d56c1f8a37e409a19352bfe
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2692906
Commit-Queue: Tim van der Lippe <tvanderlippe@chromium.org>
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
diff --git a/node_modules/object-assign/index.js b/node_modules/object-assign/index.js
new file mode 100644
index 0000000..0930cf8
--- /dev/null
+++ b/node_modules/object-assign/index.js
@@ -0,0 +1,90 @@
+/*
+object-assign
+(c) Sindre Sorhus
+@license MIT
+*/
+
+'use strict';
+/* eslint-disable no-unused-vars */
+var getOwnPropertySymbols = Object.getOwnPropertySymbols;
+var hasOwnProperty = Object.prototype.hasOwnProperty;
+var propIsEnumerable = Object.prototype.propertyIsEnumerable;
+
+function toObject(val) {
+	if (val === null || val === undefined) {
+		throw new TypeError('Object.assign cannot be called with null or undefined');
+	}
+
+	return Object(val);
+}
+
+function shouldUseNative() {
+	try {
+		if (!Object.assign) {
+			return false;
+		}
+
+		// Detect buggy property enumeration order in older V8 versions.
+
+		// https://bugs.chromium.org/p/v8/issues/detail?id=4118
+		var test1 = new String('abc');  // eslint-disable-line no-new-wrappers
+		test1[5] = 'de';
+		if (Object.getOwnPropertyNames(test1)[0] === '5') {
+			return false;
+		}
+
+		// https://bugs.chromium.org/p/v8/issues/detail?id=3056
+		var test2 = {};
+		for (var i = 0; i < 10; i++) {
+			test2['_' + String.fromCharCode(i)] = i;
+		}
+		var order2 = Object.getOwnPropertyNames(test2).map(function (n) {
+			return test2[n];
+		});
+		if (order2.join('') !== '0123456789') {
+			return false;
+		}
+
+		// https://bugs.chromium.org/p/v8/issues/detail?id=3056
+		var test3 = {};
+		'abcdefghijklmnopqrst'.split('').forEach(function (letter) {
+			test3[letter] = letter;
+		});
+		if (Object.keys(Object.assign({}, test3)).join('') !==
+				'abcdefghijklmnopqrst') {
+			return false;
+		}
+
+		return true;
+	} catch (err) {
+		// We don't expect any of the above to throw, but better to be safe.
+		return false;
+	}
+}
+
+module.exports = shouldUseNative() ? Object.assign : function (target, source) {
+	var from;
+	var to = toObject(target);
+	var symbols;
+
+	for (var s = 1; s < arguments.length; s++) {
+		from = Object(arguments[s]);
+
+		for (var key in from) {
+			if (hasOwnProperty.call(from, key)) {
+				to[key] = from[key];
+			}
+		}
+
+		if (getOwnPropertySymbols) {
+			symbols = getOwnPropertySymbols(from);
+			for (var i = 0; i < symbols.length; i++) {
+				if (propIsEnumerable.call(from, symbols[i])) {
+					to[symbols[i]] = from[symbols[i]];
+				}
+			}
+		}
+	}
+
+	return to;
+};