Move a bunch of GC related files to heap/ subdirectory

tools/gyp/v8.gyp

Index: tools/gyp/v8.gyp
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index 96dcb6d1c3ab87580434888b5c95a2f66c30e9f5..1af0d17b55a711a375dbc4ff8a6ee3933b2a05c8 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -532,8 +532,6 @@
         '../../src/full-codegen.h',
         '../../src/func-name-inferrer.cc',
         '../../src/func-name-inferrer.h',
-        '../../src/gc-tracer.cc',
-        '../../src/gc-tracer.h',
         '../../src/gdb-jit.cc',
         '../../src/gdb-jit.h',
         '../../src/global-handles.cc',
@@ -543,14 +541,27 @@
         '../../src/handles.cc',
         '../../src/handles.h',
         '../../src/hashmap.h',
-        '../../src/heap-inl.h',
         '../../src/heap-profiler.cc',
         '../../src/heap-profiler.h',
         '../../src/heap-snapshot-generator-inl.h',
         '../../src/heap-snapshot-generator.cc',
         '../../src/heap-snapshot-generator.h',
-        '../../src/heap.cc',
-        '../../src/heap.h',
+        '../../src/heap/gc-tracer.cc',
+        '../../src/heap/gc-tracer.h',
+        '../../src/heap/heap-inl.h',
+        '../../src/heap/heap.cc',
+        '../../src/heap/heap.h',
+        '../../src/heap/incremental-marking-inl.h',
+        '../../src/heap/incremental-marking.cc',
+        '../../src/heap/incremental-marking.h',
+        '../../src/heap/mark-compact-inl.h',
+        '../../src/heap/mark-compact.cc',
+        '../../src/heap/mark-compact.h',
+        '../../src/heap/spaces-inl.h',
+        '../../src/heap/spaces.cc',
+        '../../src/heap/spaces.h',
+        '../../src/heap/sweeper-thread.h',
+        '../../src/heap/sweeper-thread.cc',
         '../../src/hydrogen-alias-analysis.h',
         '../../src/hydrogen-bce.cc',
         '../../src/hydrogen-bce.h',
@@ -610,8 +621,6 @@
         '../../src/ic-inl.h',
         '../../src/ic.cc',
         '../../src/ic.h',
-        '../../src/incremental-marking.cc',
-        '../../src/incremental-marking.h',
         '../../src/interface.cc',
         '../../src/interface.h',
         '../../src/interpreter-irregexp.cc',
@@ -643,8 +652,6 @@
         '../../src/lookup.cc',
         '../../src/lookup.h',
         '../../src/macro-assembler.h',
-        '../../src/mark-compact.cc',
-        '../../src/mark-compact.h',
         '../../src/messages.cc',
         '../../src/messages.h',
         '../../src/msan.h',
@@ -712,9 +719,6 @@
         '../../src/snapshot.h',
         '../../src/snapshot-source-sink.cc',
         '../../src/snapshot-source-sink.h',
-        '../../src/spaces-inl.h',
-        '../../src/spaces.cc',
-        '../../src/spaces.h',
         '../../src/store-buffer-inl.h',
         '../../src/store-buffer.cc',
         '../../src/store-buffer.h',
@@ -726,8 +730,6 @@
         '../../src/strtod.h',
         '../../src/stub-cache.cc',
         '../../src/stub-cache.h',
-        '../../src/sweeper-thread.h',
-        '../../src/sweeper-thread.cc',
         '../../src/token.cc',
         '../../src/token.h',
         '../../src/transitions-inl.h',