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Depends on: https://github.com/lightpanda-io/zig-v8-fork/pull/153 In some ways this is an extension of https://github.com/lightpanda-io/browser/pull/1635 but it has more implications with respect to correctness. A js.Context wraps a v8::Context. One of the important thing it adds is the identity_map so that, given a Zig instance we always return the same v8::Object. But imagine code running in a frame. This frame has its own Context, and thus its own identity_map. What happens when that frame does: ```js window.top.frame_loaded = true; ``` From Zig's point of view, `Window.getTop` will return the correct Zig instance. It will return the *Window references by the "root" page. When that instance is passed to the bridge, we'll look for the v8::Object in the Context's `identity_map` but wont' find it. The mapping exists in the root context `identity_map`, but not within this frame. So we create a new v8::Object and now our 1 zig instance has N v8::Objects for every page/frame that tries to access it. This breaks cross-frame scripting which should work, at least to some degree, even when frames are on the same origin. This commit adds a `js.Origin` which contains the `identity_map`, along with our other `v8::Global` storage. The `Env` now contains a `*js.Origin` lookup, mapping an origin string (e.g. lightpanda.io:443) to an *Origin. When a Page's URL is changed, we call `self.js.setOrigin(new_url)` which will then either get or create an origin from the Env's origin lookup map. js.Origin is reference counted so that it remains valid so long as at least 1 frame references them. There's some special handling for null-origins (i.e. about:blank). At the root, null origins get a distinct/isolated Origin. For a frame, the parent's origin is used. Above, we talked about `identity_map`, but a `js.Context` has 8 other fields to track v8 values, e.g. `global_objects`, `global_functions`, `global_values_temp`, etc. These all must be shared by frames on the same origin. So all of these have also been moved to js.Origin. They've also been merged so that we now have 3 fields: `identity_map`, `globals` and `temps`. Finally, when the origin of a context is changed, we set the v8::Context's SecurityToken (to that origin). This is a key part of how v8 allows cross- context access.