move some files to more reasonable locations

src/legacy/polyfills/focusPreventScroll.js

@@ -0,0 +1,42 @@
+// Polyfill to add support for preventScroll by focus function
+
+if (HTMLElement.prototype.nativeFocus === undefined) {
+    (function () {
+        var supportsPreventScrollOption = false;
+        try {
+            var focusElem = document.createElement("div");
+
+            focusElem.addEventListener("focus", function(event) {
+                event.preventDefault();
+                event.stopPropagation();
+            }, true);
+
+            var opts = Object.defineProperty({}, "preventScroll", {
+                // eslint-disable-next-line getter-return
+                get: function () {
+                    supportsPreventScrollOption = true;
+                }
+            });
+
+            focusElem.focus(opts);
+        } catch (e) {
+            console.error("error checking preventScroll support");
+        }
+
+        if (!supportsPreventScrollOption) {
+            HTMLElement.prototype.nativeFocus = HTMLElement.prototype.focus;
+
+            HTMLElement.prototype.focus = function(options) {
+                var scrollX = window.scrollX;
+                var scrollY = window.scrollY;
+
+                this.nativeFocus();
+
+                // Restore window scroll if preventScroll
+                if (options && options.preventScroll) {
+                    window.scroll(scrollX, scrollY);
+                }
+            };
+        }
+    })();
+}