benchmark.parse-float: add a float parse benchmark.

extra/benchmark/parse-float/parse-float.factor

@@ -0,0 +1,12 @@
+USING: kernel literals math.functions math.parser random
+sequences ;
+IN: benchmark.parse-float
+
+CONSTANT: test-floats $[ 100,000 random-units ]
+
+: parse-float-benchmark ( -- )
+    test-floats [
+        [ number>string string>number ] [ 1e-10 ~ t assert= ] bi
+    ] each ;
+
+MAIN: parse-float-benchmark