[heap] make inline-allocation-observers precise

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index b3107df1008bbf8b48ac633a0093b5ef404c5100..3b197ddd66d7e7cb7edc19e6e793c33a44856ffe 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -2513,7 +2513,7 @@ class InlineAllocationObserver {
  public:
   explicit InlineAllocationObserver(intptr_t step_size)
       : step_size_(step_size), bytes_to_next_step_(step_size) {
-    DCHECK(step_size >= kPointerSize && (step_size & kHeapObjectTagMask) == 0);
+    DCHECK(step_size >= kPointerSize);
   }
   virtual ~InlineAllocationObserver() {}
 
@@ -2521,14 +2521,14 @@ class InlineAllocationObserver {
   intptr_t step_size() const { return step_size_; }
   intptr_t bytes_to_next_step() const { return bytes_to_next_step_; }
 
-  // Pure virtual method provided by the subclasses that gets called when more
-  // than step_size byte have been allocated.
+  // Pure virtual method provided by the subclasses that gets called when at
+  // least step_size byte have been allocated.

[Hannes Payer (out of office), 2015/11/17 14:41:30]

byte => bytes

   virtual void Step(int bytes_allocated) = 0;
 
   // Called each time the new space does an inline allocation step. This may be
   // more frequently than the step_size we are monitoring (e.g. when there are
   // multiple observers, or when page or space boundary is encountered.) The
-  // Step method is only called once more than step_size bytes have been
+  // Step method is only called once at least than step_size bytes have been

[Hannes Payer (out of office), 2015/11/17 14:41:30]

This sentence seems to be broken. Do we still need it?

   // allocated.
   void InlineAllocationStep(int bytes_allocated) {
     bytes_to_next_step_ -= bytes_allocated;