Fix builds w/ component=="shared_library" and v8_use_external_startup_data==1.

test/unittests/unittests.gyp

Index: test/unittests/unittests.gyp
diff --git a/test/unittests/unittests.gyp b/test/unittests/unittests.gyp
index 8a323f121403478afbbe6fe54b663b4c02b7b8a1..35c1020ce3d18ef9428008a480eeec512e467b9d 100644
--- a/test/unittests/unittests.gyp
+++ b/test/unittests/unittests.gyp
@@ -106,13 +106,14 @@
           # compiler-unittests can't be built against a shared library, so we
           # need to depend on the underlying static target in that case.
           'conditions': [
-            ['v8_use_snapshot=="true"', {
+            ['v8_use_snapshot=="true" and v8_use_external_startup_data==0', {
               'dependencies': ['../../tools/gyp/v8.gyp:v8_snapshot'],
-            },
-            {
-              'dependencies': [
-                '../../tools/gyp/v8.gyp:v8_nosnapshot',
-              ],
+            }],
+            ['v8_use_snapshot=="true" and v8_use_external_startup_data==1', {
+              'dependencies': ['../../tools/gyp/v8.gyp:v8_external_snapshot'],
+            }],
+            ['v8_use_snapshot!="true"', {
+              'dependencies': ['../../tools/gyp/v8.gyp:v8_nosnapshot'],
             }],
           ],
         }, {