Webpack already allows for specifying a trusted-types policy name. However, its current implementation is such that if a call to trustedTypes.createPolicy fails, the code will immediately stop executing. This isn't necessarily desirable, as an application could be in the early phases of rolling out trusted types, and thus have the CSP rule for trusted-types LibraryA LibraryB etc, BUT have require-trusted-types-for 'script' be in "report only" mode (Content-Security-Policy-Report-Only). In such a configuration, and when the webpacked code is dynamically-loaded into an application, adding the policy name to the webpack config will break old versions.
This PR keeps the original behavior, but introduces a new option for onPolicyCreationFailure: "continue" | "stop" (with "stop" remaining the default). If a developer chooses the "continue" option, the policy-creation will be wrapped in a try/catch. There is no security risk to this, since for host applications that DO have strict enforcement of trusted-types, the code will simply fail when the dangerous sink is used (e.g., when doing parseFromString). And likewise, wrapping in try/catch and doing nothing on catch is OK, because the code already deals with the possibility of the trustedTypes API not being available on the browser.
Since createScriptURL is the only function that is used on webpack's
Trusted Types policy, replace the getTrustedTypesPolicy global with a
simpler createScriptURL global.
In terms of compiled code, this replaces the non-minifiable
tt().createScriptURL(url) with tu(url), which is more compact in terms
of code size.
allow to execute a part of the module graph at build time
e. g. to generate code or other assets
loaders have access to that via `this.importModule(request, options)`
get rid of startupNoDefault and many custom logic regarding this in jsonp chunk loading
add onChunksLoaded runtime method to cover that for all chunk loading types
add `__webpack_runtime_id__` to access the current runtime
allow to use onChunksLoaded for other module types too