Remove wildcard from Postmessage

[HunnySajid]

Currently we are using wildcard '*' while communicating with postMessage. It is not correct as it broadcasts messages to all.
We need to fix it so that communication can only be between out content script and webpage.

Relevant links:
https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage#using_window.postmessage_in_extensions_non-standard

Linked Issue on signify-extension:
WebOfTrust/signify-browser-extension#159

[lenkan]

This is now implemented as an option:

polaris-web/src/client.ts

Line 143 in bcb5283

targetOrigin?: string;

polaris-web/src/client.ts

Line 337 in bcb5283

window.postMessage({ requestId, type, ...(payload ?? {}) }, this.options.targetOrigin ?? "/");

Is that sufficient to be able to close this? The default behavior is that the target origin is "/", which means same origin according to spec.

[HunnySajid]

@lenkan thanks for looking into it, can be closed now.