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

tools/gyp/v8.gyp

Index: tools/gyp/v8.gyp
diff --git a/tools/gyp/v8.gyp b/tools/gyp/v8.gyp
index b040ba412148503c7df2fb84166917bc15fa8ba8..d23c9bda1cc99877978c8bd448c052ef2459978e 100644
--- a/tools/gyp/v8.gyp
+++ b/tools/gyp/v8.gyp
@@ -646,9 +646,6 @@
         '../../src/compiler/value-numbering-reducer.h',
         '../../src/compiler/verifier.cc',
         '../../src/compiler/verifier.h',
-        '../../src/compiler/wasm-compiler.cc',
-        '../../src/compiler/wasm-compiler.h',
-        '../../src/compiler/wasm-linkage.cc',
         '../../src/compiler/zone-pool.cc',
         '../../src/compiler/zone-pool.h',
         '../../src/compiler.cc',
@@ -1069,24 +1066,6 @@
         '../../src/version.h',
         '../../src/vm-state-inl.h',
         '../../src/vm-state.h',
-        '../../src/wasm/asm-wasm-builder.cc',
-        '../../src/wasm/asm-wasm-builder.h',
-        '../../src/wasm/ast-decoder.cc',
-        '../../src/wasm/ast-decoder.h',
-        '../../src/wasm/decoder.h',
-        '../../src/wasm/encoder.cc',
-        '../../src/wasm/encoder.h',
-        '../../src/wasm/module-decoder.cc',
-        '../../src/wasm/module-decoder.h',
-        '../../src/wasm/wasm-js.cc',
-        '../../src/wasm/wasm-js.h',
-        '../../src/wasm/wasm-macro-gen.h',
-        '../../src/wasm/wasm-module.cc',
-        '../../src/wasm/wasm-module.h',
-        '../../src/wasm/wasm-opcodes.cc',
-        '../../src/wasm/wasm-opcodes.h',
-        '../../src/wasm/wasm-result.cc',
-        '../../src/wasm/wasm-result.h',
         '../../src/zone.cc',
         '../../src/zone.h',
         '../../src/zone-allocator.h',
@@ -1498,6 +1477,31 @@
             }, {
               'defines': ['ICU_UTIL_DATA_IMPL=ICU_UTIL_DATA_STATIC'],
             }],
+          ],
+        }],
+        ['v8_wasm!=0', {
+          'sources': [
+            '../../src/compiler/wasm-compiler.cc',
+            '../../src/compiler/wasm-compiler.h',
+            '../../src/compiler/wasm-linkage.cc',
+            '../../src/wasm/asm-wasm-builder.cc',
+            '../../src/wasm/asm-wasm-builder.h',
+            '../../src/wasm/ast-decoder.cc',
+            '../../src/wasm/ast-decoder.h',
+            '../../src/wasm/decoder.h',
+            '../../src/wasm/encoder.cc',
+            '../../src/wasm/encoder.h',
+            '../../src/wasm/module-decoder.cc',
+            '../../src/wasm/module-decoder.h',
+            '../../src/wasm/wasm-js.cc',
+            '../../src/wasm/wasm-js.h',
+            '../../src/wasm/wasm-macro-gen.h',
+            '../../src/wasm/wasm-module.cc',
+            '../../src/wasm/wasm-module.h',
+            '../../src/wasm/wasm-opcodes.cc',
+            '../../src/wasm/wasm-opcodes.h',
+            '../../src/wasm/wasm-result.cc',
+            '../../src/wasm/wasm-result.h',
           ],
         }],
       ],