Fix Heap::Shrink to ensure that it does not free pages that are still in use.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index 0cbe13f92fb26cdb730318ae56cde11cac517d23..be8dfecc0e67cac7e24270cbecf00e79558009f4 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -5609,8 +5609,11 @@ void Heap::TearDown() {
 void Heap::Shrink() {
   // Try to shrink all paged spaces.
   PagedSpaces spaces;
-  for (PagedSpace* space = spaces.next(); space != NULL; space = spaces.next())
+  for (PagedSpace* space = spaces.next();
+       space != NULL;
+       space = spaces.next()) {
     space->ReleaseAllUnusedPages();
+  }
 }