Unified the structure of VirtualMemory implementations across platforms a bit.

src/platform-freebsd.cc

Index: src/platform-freebsd.cc
diff --git a/src/platform-freebsd.cc b/src/platform-freebsd.cc
index baab4714b9d05bce55982e8722a8b52d6819883c..e9db66d9c05df61f54a64da79499958a569458f0 100644
--- a/src/platform-freebsd.cc
+++ b/src/platform-freebsd.cc
@@ -358,12 +358,12 @@ int OS::StackWalk(Vector<OS::StackFrame> frames) {
 static const int kMmapFd = -1;
 static const int kMmapFdOffset = 0;
 
+
 VirtualMemory::VirtualMemory() : address_(NULL), size_(0) { }
 
-VirtualMemory::VirtualMemory(size_t size) {
-  address_ = ReserveRegion(size);
-  size_ = size;
-}
+
+VirtualMemory::VirtualMemory(size_t size)
+    : address_(ReserveRegion(size)), size_(size) { }
 
 
 VirtualMemory::VirtualMemory(size_t size, size_t alignment)