Fix Context's call_arena

The Context's call_arena should be based on the source, e.g. the IsolateWorld
or the Page, not always the page. There's no rule that says all Contexts have
to be a subset of the Page, and thus some might live longer and by doing so
outlive the page_arena.

Also, on context cleanup, isolate worlds now cleanup their identity.

src/ArenaPool.zig

@@ -112,7 +112,6 @@ pub fn acquire(self: *ArenaPool, dbg: DebugInfo) !Allocator {
         }
         gop.value_ptr.* += 1;
     }
-
     return entry.arena.allocator();
 }
 

src/browser/Page.zig

@@ -305,6 +305,7 @@ pub fn init(self: *Page, frame_id: u32, session: *Session, parent: ?*Page) !void
     self.js = try browser.env.createContext(self, .{
         .identity = &session.identity,
         .identity_arena = session.page_arena,
+        .call_arena = self.call_arena,
     });
     errdefer self.js.deinit();
 

src/browser/js/Context.zig

@@ -63,7 +63,9 @@ templates: []*const v8.FunctionTemplate,
 // Arena for the lifetime of the context
 arena: Allocator,
 
-// The page.call_arena
+// The call_arena for this context. For main world contexts this is
+// page.call_arena. For isolated world contexts this is a separate arena
+// owned by the IsolatedWorld.
 call_arena: Allocator,
 
 // Because calls can be nested (i.e.a function calling a callback),

src/browser/js/Env.zig

@@ -258,6 +258,7 @@ pub fn deinit(self: *Env) void {
 pub const ContextParams = struct {
     identity: *js.Identity,
     identity_arena: Allocator,
+    call_arena: Allocator,
     debug_name: []const u8 = "Context",
 };
 
@@ -325,7 +326,7 @@ pub fn createContext(self: *Env, page: *Page, params: ContextParams) !*Context {
         .arena = context_arena,
         .handle = context_global,
         .templates = self.templates,
-        .call_arena = page.call_arena,
+        .call_arena = params.call_arena,
         .microtask_queue = microtask_queue,
         .script_manager = &page._script_manager,
         .scheduler = .init(context_arena),

src/cdp/cdp.zig

@@ -492,9 +492,13 @@ pub fn BrowserContext(comptime CDP_T: type) type {
             const arena = try browser.arena_pool.acquire(.{ .debug = "IsolatedWorld" });
             errdefer browser.arena_pool.release(arena);
 
+            const call_arena = try browser.arena_pool.acquire(.{ .debug = "IsolatedWorld.call_arena" });
+            errdefer browser.arena_pool.release(call_arena);
+
             const world = try arena.create(IsolatedWorld);
             world.* = .{
                 .arena = arena,
+                .call_arena = call_arena,
                 .context = null,
                 .browser = browser,
                 .name = try arena.dupe(u8, world_name),
@@ -745,6 +749,7 @@ pub fn BrowserContext(comptime CDP_T: type) type {
 /// An object id is unique across all contexts, different object ids can refer to the same Node in different contexts.
 const IsolatedWorld = struct {
     arena: Allocator,
+    call_arena: Allocator,
     browser: *Browser,
     name: []const u8,
     context: ?*js.Context = null,
@@ -757,6 +762,7 @@ const IsolatedWorld = struct {
     pub fn deinit(self: *IsolatedWorld) void {
         self.removeContext() catch {};
         self.identity.deinit();
+        self.browser.arena_pool.release(self.call_arena);
         self.browser.arena_pool.release(self.arena);
     }
 
@@ -764,6 +770,8 @@ const IsolatedWorld = struct {
         const ctx = self.context orelse return error.NoIsolatedContextToRemove;
         self.browser.env.destroyContext(ctx);
         self.context = null;
+        self.identity.deinit();
+        self.identity = .{};
     }
 
     // The isolate world must share at least some of the state with the related page, specifically the DocumentHTML
@@ -776,6 +784,7 @@ const IsolatedWorld = struct {
             const ctx = try self.browser.env.createContext(page, .{
                 .identity = &self.identity,
                 .identity_arena = self.arena,
+                .call_arena = self.call_arena,
                 .debug_name = "IsolatedContext",
             });
             self.context = ctx;