rails/rails — pull request #17211 by huacnlee (2014-10-08 15:00:43+00:00)
Title: reduce allocations and change some String process methods for asset_path helper

~ 20% performance up

benchmark: https://gist.github.com/huacnlee/96374e46bb35c7351878

```
## Before

Total allocated 13
Total retained 0

## After

Total allocated 4
Total retained 1

## Benchmark

Calculating -------------------------------------
asset_path before 9196 i/100ms
asset_path after 10588 i/100ms
-------------------------------------------------
asset_path before 112359.4 (±5.7%) i/s - 560956 in 5.008435s
asset_path after 134550.6 (±6.0%) i/s - 677632 in 5.054601s

Comparison:
asset_path after: 134550.6 i/s
asset_path before: 112359.4 i/s - 1.20x slower
```