[modules] Introduce new VariableLocation for module imports/exports.

src/full-codegen/ia32/full-codegen-ia32.cc

Index: src/full-codegen/ia32/full-codegen-ia32.cc
diff --git a/src/full-codegen/ia32/full-codegen-ia32.cc b/src/full-codegen/ia32/full-codegen-ia32.cc
index 1372a21f61fbb6be653bf69705fc3b25057c4f20..1620905a77c60732acd35558cf2ea3769e3c2bd0 100644
--- a/src/full-codegen/ia32/full-codegen-ia32.cc
+++ b/src/full-codegen/ia32/full-codegen-ia32.cc
@@ -750,6 +750,9 @@ void FullCodeGenerator::VisitVariableDeclaration(
       PrepareForBailoutForId(proxy->id(), BailoutState::NO_REGISTERS);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }
 
@@ -805,6 +808,9 @@ void FullCodeGenerator::VisitFunctionDeclaration(
       PrepareForBailoutForId(proxy->id(), BailoutState::NO_REGISTERS);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }
 
@@ -1275,6 +1281,9 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy,
       context()->Plug(eax);
       break;
     }
+
+    case VariableLocation::MODULE:
+      UNREACHABLE();
   }
 }