esbuild 0.11.20

Omit warning about duplicate JSON keys from inside node_modules (#1254)

This release no longer warns about duplicate keys inside package.json files inside node_modules. There are packages like this that are published to npm, and this warning is unactionable. Now esbuild will only issue this warning outside of node_modules directories.
Add CSS minification for box-shadow values

The CSS box-shadow property is now minified when --mangle-syntax is enabled. This includes trimming length values and minifying color representations.
Fix object spread transform for non-spread getters (#1259)

When transforming an object literal containing object spread (the ... syntax), properties inside the spread should be evaluated but properties outside the spread should not be evaluated. Previously esbuild's object spread transform incorrectly evaluated properties in both cases. Consider this example:
```
var obj = {
  ...{ get x() { console.log(1) } },
  get y() { console.log(3) },
}
console.log(2)
obj.y
```
This should print out 1 2 3 because the non-spread getter should not be evaluated. Instead, esbuild was incorrectly transforming this into code that printed 1 3 2. This issue should now be fixed with this release.
Prevent private class members from being added more than once

This fixes a corner case with the private class member implementation. Constructors in JavaScript can return an object other than this, so private class members can actually be added to objects other than this. This can be abused to attach completely private metadata to other objects:
```
class Base {
  constructor(x) {
    return x
  }
}
class Derived extends Base {
  #y
  static is(z) {
    return #y in z
  }
}
const foo = {}
new Derived(foo)
console.log(Derived.is(foo)) // true
```
This already worked in code transformed by esbuild for older browsers. However, calling new Derived(foo) multiple times in the above code was incorrectly allowed. This should not be allowed because it would mean that the private field #y would be re-declared. This is no longer allowed starting from this release.