Fix typo.

src/platform/virtual-memory.h

Index: src/platform/virtual-memory.h
diff --git a/src/platform/virtual-memory.h b/src/platform/virtual-memory.h
index 858c862b764d45e25441354ced59f850676ce099..73ba24dcebe7acbc05a379efd50b516e76f57307 100644
--- a/src/platform/virtual-memory.h
+++ b/src/platform/virtual-memory.h
@@ -39,8 +39,8 @@ namespace internal {
 //
 // This class represents and controls an area of reserved memory.
 // Control of the reserved memory can be assigned to another VirtualMemory
-// object by assignment or contructing. This removes the reserved memory from
-// the original object.
+// object by assignment or copy-constructing. This removes the reserved memory
+// from the original object.
 class VirtualMemory V8_FINAL {
  public:
   // The executability of a memory region.