Profiler improvements

test/mjsunit/tools/tickprocessor-test.default

 Statistical profiling result from v8.log, (13 ticks, 2 unaccounted, 0 excluded).
 
  [Shared libraries]:
    ticks  total  nonlib   name
       3   23.1%          /lib32/libm-2.7.so
       1    7.7%          ffffe000-fffff000
 
  [JavaScript]:
    ticks  total  nonlib   name
-      1    7.7%   11.1%  LazyCompile: exp native math.js:41
 
  [C++]:
    ticks  total  nonlib   name
       2   15.4%   22.2%  v8::internal::Runtime_Math_exp(v8::internal::Arguments)
       1    7.7%   11.1%  v8::internal::JSObject::LookupOwnRealNamedProperty(v8::internal::String*, v8::internal::LookupResult*)
       1    7.7%   11.1%  v8::internal::HashTable<v8::internal::StringDictionaryShape, v8::internal::String*>::FindEntry(v8::internal::String*)
       1    7.7%   11.1%  exp
 
  [Summary]:
    ticks  total  nonlib   name
-      1    7.7%   11.1%  JavaScript
+      0    0.0%    0.0%  JavaScript
       5   38.5%   55.6%  C++
       0    0.0%    0.0%  GC
       4   30.8%          Shared libraries
       2   15.4%          Unaccounted
 
  [C++ entry points]:
    ticks    cpp   total   name
       2   40.0%   15.4%  v8::internal::Runtime_Math_exp(v8::internal::Arguments)
       1   20.0%    7.7%  v8::internal::JSObject::LookupOwnRealNamedProperty(v8::internal::String*, v8::internal::LookupResult*)
       1   20.0%    7.7%  v8::internal::HashTable<v8::internal::StringDictionaryShape, v8::internal::String*>::FindEntry(v8::internal::String*)
       1   20.0%    7.7%  exp
 
  [Bottom up (heavy) profile]:
   Note: percentage shows a share of a particular caller in the total
   amount of its parent calls.
   Callers occupying less than 2.0% are not shown.
 
    ticks parent  name
       3   23.1%  /lib32/libm-2.7.so
       3  100.0%    LazyCompile: exp native math.js:41
       3  100.0%      Script: exp.js
 
       2   15.4%  v8::internal::Runtime_Math_exp(v8::internal::Arguments)
       2  100.0%    LazyCompile: exp native math.js:41
       2  100.0%      Script: exp.js
 
+      2   15.4%  UNKNOWN
+      1   50.0%    LazyCompile: exp native math.js:41
+      1  100.0%      Script: exp.js
+
       1    7.7%  v8::internal::JSObject::LookupOwnRealNamedProperty(v8::internal::String*, v8::internal::LookupResult*)
       1  100.0%    Script: exp.js
 
       1    7.7%  v8::internal::HashTable<v8::internal::StringDictionaryShape, v8::internal::String*>::FindEntry(v8::internal::String*)
       1  100.0%    Script: exp.js
 
       1    7.7%  ffffe000-fffff000
 
       1    7.7%  exp
       1  100.0%    LazyCompile: exp native math.js:41
       1  100.0%      Script: exp.js
 
-      1    7.7%  LazyCompile: exp native math.js:41
-      1  100.0%    Script: exp.js
-