Nathan Shively-Sanders a52805f641 Use checkExpression in checkSpreadExpression
Not checkExpressionCached. checkExpressionCached ignores ongoing control
flow analysis, which causes the following loop to make the compiler
recur infinitely:

```ts
let a = []
for (const x of []) {
    a = [...a]
}
```
2016-12-09 10:50:14 -08:00
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