PPC: Fixed RememberedSetRemoveRange to have chunk->size > PageSize

Increased array size in the testcase such that the chunk size is
greater that the page size on PPC (4MB). This fixes the case when
(start + Page::kPageSize) memory location is tested to be part of
the chunk.
The testcase was added as part of https://codereview.chromium.org/2110213003/

R=ulan@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com

BUG=
LOG=N

Review-Url: https://codereview.chromium.org/2182113002
Cr-Commit-Position: refs/heads/master@{#38060}

test/cctest/heap/test-heap.cc

@@ -6872,7 +6872,8 @@ TEST(RememberedSetRemoveRange) {
   Heap* heap = CcTest::heap();
   Isolate* isolate = heap->isolate();
 
-  Handle<FixedArray> array = isolate->factory()->NewFixedArray(500000);
+  Handle<FixedArray> array = isolate->factory()->NewFixedArray(Page::kPageSize /
+                                                              kPointerSize);
   MemoryChunk* chunk = MemoryChunk::FromAddress(array->address());
   CHECK(chunk->owner()->identity() == LO_SPACE);
   Address start = array->address();