Added behind link_core_modules_separately flag to gyp files.

Source/build/features.gypi

Index: Source/build/features.gypi
diff --git a/Source/build/features.gypi b/Source/build/features.gypi
index e990d073c469883116e21408b81fe8dc2224cee5..a87c0442b8100abb1538d0cb7de036b1cf2959d4 100644
--- a/Source/build/features.gypi
+++ b/Source/build/features.gypi
@@ -48,6 +48,7 @@
       'enable_oilpan%': 0,
       'blink_gc_profiling%': 0,
       'blink_logging_always_on%': 0,
+      'link_core_modules_separately%': 0,
     },
     'conditions': [
       ['use_concatenated_impulse_responses==1', {
@@ -94,6 +95,14 @@
           'LOG_DISABLED=0',
         ],
       }],
+      ['link_core_modules_separately==1', {
+        'feature_defines': [
+          'LINK_CORE_MODULES_SEPARATELY',
+        ],
+      }],
     ],
+
+    # shared build only. If set to 1, link web, core and modules separately.
+    'link_core_modules_separately%': '<(link_core_modules_separately)',
   },
 }