Add a dumb renderer to get coordinates

FlatRenderer positions items on a single row, giving each a height and width of
1.

Added getBoundingClientRect to the DOMelement which, when requested for the
first time, will place the item in with the renderer.

The goal here is to give elements a fixed position and to make it easy to map
x,y coordinates onto an element. This should work, at least with puppeteer,
since it first requests the boundingClientRect before issuing a click.

src/cdp/domains/page.zig

@@ -129,6 +129,18 @@ fn createIsolatedWorld(cmd: anytype) !void {
 }
 
 fn navigate(cmd: anytype) !void {
+    const params = (try cmd.params(struct {
+        url: []const u8,
+        // referrer: ?[]const u8 = null,
+        // transitionType: ?[]const u8 = null, // TODO: enum
+        // frameId: ?[]const u8 = null,
+        // referrerPolicy: ?[]const u8 = null, // TODO: enum
+    })) orelse return error.InvalidParams;
+
+    return navigateToUrl(cmd, params.url, true);
+}
+
+pub fn navigateToUrl(cmd: anytype, url: []const u8, send_result: bool) !void {
     const bc = cmd.browser_context orelse return error.BrowserContextNotLoaded;
 
     // didn't create?
@@ -140,20 +152,10 @@ fn navigate(cmd: anytype) !void {
     // if we have a target_id we have to have a page;
     std.debug.assert(bc.session.page != null);
 
-    const params = (try cmd.params(struct {
-        url: []const u8,
-        referrer: ?[]const u8 = null,
-        transitionType: ?[]const u8 = null, // TODO: enum
-        frameId: ?[]const u8 = null,
-        referrerPolicy: ?[]const u8 = null, // TODO: enum
-    })) orelse return error.InvalidParams;
-
     // change state
     bc.reset();
-    bc.url = params.url;
-
-    // TODO: hard coded ID
-    bc.loader_id = "AF8667A203C5392DBE9AC290044AA4C2";
+    bc.url = url;
+    bc.loader_id = cmd.cdp.loader_id_gen.next();
 
     const LifecycleEvent = struct {
         frameId: []const u8,
@@ -180,10 +182,12 @@ fn navigate(cmd: anytype) !void {
     }
 
     // output
-    try cmd.sendResult(.{
-        .frameId = target_id,
-        .loaderId = bc.loader_id,
-    }, .{});
+    if (send_result) {
+        try cmd.sendResult(.{
+            .frameId = target_id,
+            .loaderId = bc.loader_id,
+        }, .{});
+    }
 
     // TODO: at this point do we need async the following actions to be async?
 
@@ -199,7 +203,7 @@ fn navigate(cmd: anytype) !void {
     );
 
     var page = bc.session.currentPage().?;
-    try page.navigate(params.url, aux_data);
+    try page.navigate(url, aux_data);
 
     // Events
 
@@ -218,7 +222,7 @@ fn navigate(cmd: anytype) !void {
         .type = "Navigation",
         .frame = Frame{
             .id = target_id,
-            .url = bc.url,
+            .url = url,
             .securityOrigin = bc.security_origin,
             .secureContextType = bc.secure_context_type,
             .loaderId = bc.loader_id,