asm-llvm: reduce the number of ConstantBinding and TempBinding objects created.
asm-llvm: further reduce ConstantBinding creation.

Running some code to gather statistics on the number of integer constant
objects created, the result (summed across the arewefastyet benchmarks) was:

... constants encountered fewer than 1,000 times elided ...
1009 times for constant 1328
1255 times for constant 32
1289 times for constant 20
2323 times for constant 3
2328 times for constant -1
2421 times for constant 24
3336 times for constant 12
5848 times for constant 16
6205 times for constant 8
7012 times for constant 4
12203 times for constant 1
50835 times for constant 2

So we added INT_ONE and INT_TWO to our list of preallocated constant objects.
asm-llvm: add _ to exported tokTypes to match upstream acorn.

This is upstream commit
https://github.com/marijnh/acorn/commit/6fe123947be30cb565b4d575cbe3879c4ccd9672
asm-llvm: Don't assume options object has a hasOwnProperty method.

This matches upstream commit
https://github.com/marijnh/acorn/commit/adf16e33c0e1610ce26bf46ba0bd126943f4596b
Allow (and ignore) "use strict" as first statement in a TurtleScript function.
Correct some grammar in the benchmarks page.
Benchmarks: turn off location tracking; add 'tokenizeOnly' mode to acorn parser.
Make Function.prototype.New() faster on v8.