Fixed bug. Looking for focusedOption can return incorrect value in ca…

…se when focusedOption not equal to any element of array, IE compatible

src/Select.js

@@ -1009,7 +1009,14 @@ const Select = React.createClass({
 
 		let focusedOption = this.state.focusedOption || selectedOption;
 		if (focusedOption && !focusedOption.disabled) {
-			const focusedOptionIndex = options.findIndex(option => option.value === focusedOption.value);
+			let focusedOptionIndex = -1;
+			options.some((option, index) => {
+				const isOptionEqual = option.value === focusedOption.value;
+				if (isOptionEqual) {
+					focusedOptionIndex = index;
+				}
+				return isOptionEqual;
+			});
 			if (focusedOptionIndex !== -1) {
 				return focusedOptionIndex;
 			}