fix: pause dep collection during immediate watcher invocation

[delaneyb]

Close #11942

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• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe: Performance improvement

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• Yes
• No

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• New/updated tests are included

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Other information:

[posva]

can you add a unit test?

[delaneyb]

Related Vue 3 PR: vuejs/core#2765

I see the solution there pauses tracking during both the immediate and subsequent invocations, whereas my issue here covers only that immediate case. Would wrapping the calls here too interfere with other uses of the Watcher class?

vue/src/core/observer/watcher.js

Lines 193 to 201 in 5255841

	if (this.user) {
	try {
	this.cb.call(this.vm, value, oldValue)
	} catch (e) {
	handleError(e, this.vm, `callback for watcher "${this.expression}"`)
	}
	} else {
	this.cb.call(this.vm, value, oldValue)
	}

[posva]

Thanks!