Pass value through to PROPERTY_DID_CHANGE to avoid calling get when setting values for computed props

[brendenpalmer]

As part of trying to upgrade our application from 3.12 -> 3.16, I discovered a regression where setting a value for a computed property, then immediately retrieving that value would return undefined. In our test suite and application this causes subtle bugs and unexpected behavior. With help from @pzuraq, we were able to trace this down to PROPERTY_DID_CHANGE firing at the wrong time, specifically for computed properties.

As part of this I also removed an unused setWithSuspend method.

Note that I confirmed that this test case passes on lts-3-12.

[rwjblue]

FYI - Linting is failing:

$ yarn lint:tsc && yarn lint:tslint && yarn lint:eslint && yarn lint:docs
$ tsc --noEmit
packages/@ember/-internals/metal/lib/computed.ts(261,11): error TS6133: '_suspended' is declared but its value is never read.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

[pzuraq]

Discussed this with @rwjblue this morning, and we realized a better solution here would be to pass the value optionally as the last argument to notifyPropertyChange here. This way, PROPERTY_DID_CHANGE can receive the value for this use case, and otherwise lookup the value if its undefined, and we don't have to call PROPERTY_DID_CHANGE again later on and copy all that logic.

[brendenpalmer]

Thanks for the review! I just updated the PR to pass the value through to notifyPropertyChange, then to PROPERTY_DID_CHANGE to avoid calling get.

[pzuraq]

Thanks a ton @brendenpalmer! If you could cherry-pick this onto master as well that'd be super helpful!