Clean up and clarify PartitionAlloc

Source/wtf/PartitionAlloc.h

Index: Source/wtf/PartitionAlloc.h
diff --git a/Source/wtf/PartitionAlloc.h b/Source/wtf/PartitionAlloc.h
index e2e68733ed2ff1a35b4217e13f446a5d3c62b97a..d0c22ac9e3995a57704b00c46970a4cca9de7375 100644
--- a/Source/wtf/PartitionAlloc.h
+++ b/Source/wtf/PartitionAlloc.h
@@ -141,10 +141,10 @@ static const size_t kMaxPartitionPagesPerSlotSpan = 4;
 
 // To avoid fragmentation via never-used freelist entries, we hand out partition
 // freelist sections gradually, in units of the dominant system page size.
-// What we're actually doing is avoiding filling the full partition page
-// (typically 16KB) will freelist pointers right away. Writing freelist
-// pointers will fault and dirty a private page, which is very wasteful if we
-// never actually store objects there.
+// What we're actually doing is avoiding filling the full partition page (16 KB)
+// with freelist pointers right away. Writing freelist pointers will fault and
+// dirty a private page, which is very wasteful if we never actually store
+// objects there.
 static const size_t kNumSystemPagesPerPartitionPage = kPartitionPageSize / kSystemPageSize;
 static const size_t kMaxSystemPagesPerSlotSpan = kNumSystemPagesPerPartitionPage * kMaxPartitionPagesPerSlotSpan;
 
@@ -726,7 +726,7 @@ ALWAYS_INLINE void partitionFreeGeneric(PartitionRootGeneric* root, void* ptr)
 #endif
 }
 
-ALWAYS_INLINE size_t partitionDirectMapSize(size_t size)
+ALWAYS_INLINE size_t partitionRoundUpToSystemPage(size_t size)
 {
     // Caller must check that the size is not above the kGenericMaxDirectMapped
     // limit before calling. This also guards against integer overflow in the
@@ -749,7 +749,7 @@ ALWAYS_INLINE size_t partitionAllocActualSize(PartitionRootGeneric* root, size_t
         // Too large to allocate => return the size unchanged.
     } else {
         ASSERT(bucket == &PartitionRootBase::gPagedBucket);
-        size = partitionDirectMapSize(size);
+        size = partitionRoundUpToSystemPage(size);
     }
     return partitionCookieSizeAdjustSubtract(size);
 #endif