fix: Fix ECMAScript analyzer (#8656)
### Description
I faced this bug while working on
https://github.com/vercel/turbo/pull/8523. Tree shaking inevitably
creates direct imports for let bindings, and when the LHS of `+=` is
imported/exported, it triggers a bug.
The problematic input file looks like
```js
// Combined load times for loading client components
let clientComponentLoadStart = 0
let clientComponentLoadTimes = 0
let clientComponentLoadCount = 0
export function wrapClientComponentLoader(ComponentMod: any) {
if (!('performance' in globalThis)) {
return ComponentMod.__next_app__
}
return {
require: (...args: any[]) => {
const startTime = performance.now()
if (clientComponentLoadStart === 0) {
clientComponentLoadStart = startTime
}
try {
clientComponentLoadCount += 1
return ComponentMod.__next_app__.require(...args)
} finally {
clientComponentLoadTimes += performance.now() - startTime
}
},
loadChunk: (...args: any[]) => {
const startTime = performance.now()
try {
clientComponentLoadCount += 1
return ComponentMod.__next_app__.loadChunk(...args)
} finally {
clientComponentLoadTimes += performance.now() - startTime
}
},
}
}
export function getClientComponentLoaderMetrics(
options: { reset?: boolean } = {}
) {
const metrics =
clientComponentLoadStart === 0
? undefined
: {
clientComponentLoadStart,
clientComponentLoadTimes,
clientComponentLoadCount,
}
if (options.reset) {
clientComponentLoadStart = 0
clientComponentLoadTimes = 0
clientComponentLoadCount = 0
}
return metrics
}
```
and it works if I apply this PR or I replace `clientComponentLoadTimes
+= performance.now() - startTime` with `clientComponentLoadTimes =
clientComponentLoadTimes + performance.now() - startTime`.
### Testing Instructions
Test references changed quite a lot.
