Get the path to the frontmost app if it's Safari or Webkit, fallsback to default browser.

target_browser.m

// ## compile this with:
// clang                            \
//   -framework Foundation          \
//   -framework AppKit              \
//   -framework ApplicationServices \
//   -fobjc-gc-only                 \
//   -o target_browser              \
//    target_browser.m

#import <Foundation/Foundation.h>
#import <AppKit/AppKit.h>
#import <ApplicationServices/ApplicationServices.h>

int main (int argc, const char * argv[]) {
  NSWorkspace  *workspace            = [NSWorkspace sharedWorkspace];
  NSDictionary *frontmostApplication = [workspace activeApplication];
  NSString     *appName              = [frontmostApplication objectForKey:@"NSApplicationName"];
  NSString     *browserBundleId      = [appName isEqualToString:@"WebKit"] || [appName isEqualToString:@"Safari"] ?
                                         [frontmostApplication objectForKey:@"NSApplicationBundleIdentifier"]     :
                                         (NSString*) LSCopyDefaultHandlerForURLScheme((CFStringRef) @"http");

  printf("%s\n", [[workspace absolutePathForAppBundleWithIdentifier:browserBundleId] UTF8String]);
  return 0;
}

Sample run:

$ ./target_browser 
/Applications/WebKit.app

This is part of http://stdout.caiochassot.com/post/2969463643/writing-applescripts-that-dynamically-target-either