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Mofei Zhang
01a6502baa
How Forget currently lowers PropertyCall:
```js
// source: [[ calleeExpr ]].propertyName( [[ argExpr0 ]])
$0 = [[ calleeExpr ]]
$1 = [[ argExpr0 ]]
$2 = PropertyCall callee=$0 property="propertyName" args=[$1]
```
This PR changes the lowering:
```js
// source: [[ calleeExpr ]].propertyName( [[ argExpr0 ]])
$0 = [[ calleeExpr ]]
$1 = PropertyLoad $0 "propertyName"
$2 = [[ argExpr0 ]]
$3 = PropertyCall callee=$0 fn=$1 args=[$2]
```
From my understanding, `PropertyCall` needs the receiver to properly model JS
semantics which is something like `resolvedFn.apply(resolvedCallee, arg0, arg1,
...)`. This is additionally useful for:
- Fine-grained mutability / alias analysis. The property call is technically a
read of the resolved function, and a mutate of the callee.
- Dependency tracking. While we could special case PropertyCall, this
representation would correctly add both callee and callee.propertyName as
dependencies for PropertyCall.
e.g.
```js
let x = [];
mutate(x);
useFreeze(x);
let y = {};
y.a = x.bar();
return y;
```