Slightly more realistic comparison for `try()`

Paging @jdalton ... This changes the try benchmark for a more realistic comparison. Most people don't wrap a single function call in a try block, they do a few things together. Hopefully this reflects that intent better than before.

#### V8 
```
Native try {} catch (e) {} vs fast.try()
    ✓  try...catch x 102,168 ops/sec ±1.77% (85 runs sampled)
    ✓  fast.try() x 2,554,906 ops/sec ±1.61% (87 runs sampled)

    Result: fast.js is 2400.69% faster than try...catch.

 Native try {} catch (e) {} vs fast.try() (single function call)
    ✓  try...catch x 102,717 ops/sec ±2.33% (81 runs sampled)
    ✓  fast.try() x 2,697,662 ops/sec ±1.64% (81 runs sampled)

    Result: fast.js is 2526.31% faster than try...catch.

```

#### SpiderMonkey
```
Native try {} catch (e) {} vs fast.try()
    ✓  try...catch x 78,420 ops/sec ±1.34% (63 runs sampled)
    ✓  fast.try() x 3,628,394 ops/sec ±0.67% (64 runs sampled)

    Result: fast.js is 4526.86% faster than try...catch.


Native try {} catch (e) {} vs fast.try() (single function call)
    ✓  try...catch x 53,455 ops/sec ±1.58% (61 runs sampled)
    ✓  fast.try() x 3,541,333 ops/sec ±0.28% (65 runs sampled)

    Result: fast.js is 6524.92% faster than try...catch.

```