Revert of Remove wasm compile time option and enable wasm behind a runtime flag.

test/cctest/cctest.gyp

Index: test/cctest/cctest.gyp
diff --git a/test/cctest/cctest.gyp b/test/cctest/cctest.gyp
index 5d0bbfe004e956d926840e730d7f3138e5cb3936..4e4674e6cfce8f1f2150d84e7e485ab1b462a598 100644
--- a/test/cctest/cctest.gyp
+++ b/test/cctest/cctest.gyp
@@ -183,9 +183,6 @@
         'test-weakmaps.cc',
         'test-weaksets.cc',
         'trace-extension.cc',
-        'wasm/test-run-wasm.cc',
-        'wasm/test-run-wasm-module.cc',
-        'wasm/test-signatures.h',
       ],
       'conditions': [
         ['v8_target_arch=="ia32"', {
@@ -301,6 +298,13 @@
           'dependencies': ['../../tools/gyp/v8.gyp:v8_maybe_snapshot'],
         }, {
           'dependencies': ['../../tools/gyp/v8.gyp:v8'],
+        }],
+        ['v8_wasm!=0', {
+          'sources': [
+            'wasm/test-run-wasm.cc',
+            'wasm/test-run-wasm-module.cc',
+            'wasm/test-signatures.h',
+          ],
         }],
       ],
     },