Fix bundler bug with var nested inside if (#​4348)

This release fixes a bug with the bundler that happens when importing an ES module using require (which causes it to be wrapped) and there's a top-level var inside an if statement without being wrapped in a { ... } block (and a few other conditions). The bundling transform needed to hoist these var declarations outside of the lazy ES module wrapper for correctness. See the issue for details.

Fix minifier bug with for inside try inside label (#​4351)

This fixes an old regression from version v0.21.4. Some code was introduced to move the label inside the try statement to address a problem with transforming labeled for await loops to avoid the await (the transformation involves converting the for await loop into a for loop and wrapping it in a try statement). However, it introduces problems for cross-compiled JVM code that uses all three of these features heavily. This release restricts this transform to only apply to for loops that esbuild itself generates internally as part of the for await transform. Here is an example of some affected code:

// Original code
d: {
  e: {
    try {
      while (1) { break d }
    } catch { break e; }
  }
}

// Old output (with --minify)
a:try{e:for(;;)break a}catch{break e}

// New output (with --minify)
a:e:try{for(;;)break a}catch{break e}

Inline IIFEs containing a single expression (#​4354)

Previously inlining of IIFEs (immediately-invoked function expressions) only worked if the body contained a single return statement. Now it should also work if the body contains a single expression statement instead:

// Original code
const foo = () => {
  const cb = () => {
    console.log(x())
  }
  return cb()
}

// Old output (with --minify)
const foo=()=>(()=>{console.log(x())})();

// New output (with --minify)
const foo=()=>{console.log(x())};

The minifier now strips empty finally clauses (#​4353)

This improvement means that finally clauses containing dead code can potentially cause the associated try statement to be removed from the output entirely in minified builds:

// Original code
function foo(callback) {
  if (DEBUG) stack.push(callback.name);
  try {
    callback();
  } finally {
    if (DEBUG) stack.pop();
  }
}

// Old output (with --minify --define:DEBUG=false)
function foo(a){try{a()}finally{}}

// New output (with --minify --define:DEBUG=false)
function foo(a){a()}

Allow tree-shaking of the Symbol constructor

With this release, calling Symbol is now considered to be side-effect free when the argument is known to be a primitive value. This means esbuild can now tree-shake module-level symbol variables:

// Original code
const a = Symbol('foo')
const b = Symbol(bar)

// Old output (with --tree-shaking=true)
const a = Symbol("foo");
const b = Symbol(bar);

// New output (with --tree-shaking=true)
const b = Symbol(bar);