Fix arrow function body parsing#1
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We add three failing tests:
1. {()=>{};``}
2. {x=>x;``}
3. {f:x=>x,y:2}
We also add a fourth test mirroring the third but with a function block
body instead of an expression. The hope is that we get no regressions
when we change the representation of arrow functions.
The issue with the current parsing rules and representation is that arrow function bodies are not statements, they're either function blocks or expressions. Looking at the specification (https://www.ecma-international.org/ecma-262/#prod-ExpressionBody) we see that the expressions are `AssignmentExpression` in particular. Making this change appears to fix the additional tests, but it breaks minification.
The minifier was treating arrow functions with block bodies incorrectly
if they contained a single expression statement with no return
statement. It was transforming them into arrow functions with expression
bodies.
This means for instance that in
```js
let x = (() => { 42 })();
```
`x` would equal `undefined` before minification, but would equal `42`
after minification. The fix is to change the tests to match the correct
behavior.
DanBurton
changed the title
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See: quintenkasteel#117