add # of plugin visits

[hzoo]

Not actually sure how useful this is anymore but figured I'd post it anyway.

./scripts/plugin-timing.js ./scripts/fixtures/jquery.js
pluginAlias                             time(ms) # visits time/visit(ms)
minify-simplify                         2461.853 53786    0.046
minify-mangle-names                     1785.353 1        1785.353
minify-constant-folding                 776.446  124070   0.006
minify-guarded-expressions              358.347  11517    0.031
minify-dead-code-elimination            250.410  1        250.410
minify-infinity                         109.801  56557    0.002
internal.shadowFunctions                105.693  57862    0.002
transform-undefined-to-void             99.388   56557    0.002
minify-type-constructors                59.929   7575     0.008
transform-simplify-comparison-operators 47.390   4845     0.010
transform-member-expression-literals    32.877   17182    0.002
minify-flip-comparisons                 17.091   4845     0.004
transform-merge-sibling-variables       7.737    1748     0.004
internal.blockHoist                     6.170    2484     0.002
transform-property-literals             4.608    1336     0.003
transform-minify-booleans               3.899    243      0.016
minify-replace                          0.186    1        0.186

[kangax]

I suppose it doesn't hurt :)

[hzoo]

Also wow that's a lot of visits