lib: use standard property names

The standard property names that aren't strings can be used where
appropiate, this is one of them.

PR-URL: nodejs#39981
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Michael Dawson <midawson@redhat.com>

lib/v8.js

@@ -154,17 +154,17 @@ function getHeapStatistics() {
   updateHeapStatisticsBuffer();
 
   return {
-    'total_heap_size': buffer[kTotalHeapSizeIndex],
-    'total_heap_size_executable': buffer[kTotalHeapSizeExecutableIndex],
-    'total_physical_size': buffer[kTotalPhysicalSizeIndex],
-    'total_available_size': buffer[kTotalAvailableSize],
-    'used_heap_size': buffer[kUsedHeapSizeIndex],
-    'heap_size_limit': buffer[kHeapSizeLimitIndex],
-    'malloced_memory': buffer[kMallocedMemoryIndex],
-    'peak_malloced_memory': buffer[kPeakMallocedMemoryIndex],
-    'does_zap_garbage': buffer[kDoesZapGarbageIndex],
-    'number_of_native_contexts': buffer[kNumberOfNativeContextsIndex],
-    'number_of_detached_contexts': buffer[kNumberOfDetachedContextsIndex]
+    total_heap_size: buffer[kTotalHeapSizeIndex],
+    total_heap_size_executable: buffer[kTotalHeapSizeExecutableIndex],
+    total_physical_size: buffer[kTotalPhysicalSizeIndex],
+    total_available_size: buffer[kTotalAvailableSize],
+    used_heap_size: buffer[kUsedHeapSizeIndex],
+    heap_size_limit: buffer[kHeapSizeLimitIndex],
+    malloced_memory: buffer[kMallocedMemoryIndex],
+    peak_malloced_memory: buffer[kPeakMallocedMemoryIndex],
+    does_zap_garbage: buffer[kDoesZapGarbageIndex],
+    number_of_native_contexts: buffer[kNumberOfNativeContextsIndex],
+    number_of_detached_contexts: buffer[kNumberOfDetachedContextsIndex]
   };
 }
 
@@ -209,9 +209,9 @@ function getHeapCodeStatistics() {
 
   updateHeapCodeStatisticsBuffer();
   return {
-    'code_and_metadata_size': buffer[kCodeAndMetadataSizeIndex],
-    'bytecode_and_metadata_size': buffer[kBytecodeAndMetadataSizeIndex],
-    'external_script_source_size': buffer[kExternalScriptSourceSizeIndex]
+    code_and_metadata_size: buffer[kCodeAndMetadataSizeIndex],
+    bytecode_and_metadata_size: buffer[kBytecodeAndMetadataSizeIndex],
+    external_script_source_size: buffer[kExternalScriptSourceSizeIndex]
   };
 }