Fix build failures with LLVM-GCC 4.2 on Mac.

src/compiler/common-operator.h

Index: src/compiler/common-operator.h
diff --git a/src/compiler/common-operator.h b/src/compiler/common-operator.h
index f7f365d4439ba1d27e352437ccff86d20c56d9cd..d5252877b0440b1cb985a40510fd75ee986afcac 100644
--- a/src/compiler/common-operator.h
+++ b/src/compiler/common-operator.h
@@ -24,7 +24,8 @@ class ControlOperator : public Operator1<int> {
  public:
   ControlOperator(IrOpcode::Value opcode, uint16_t properties, int inputs,
                   int outputs, int controls, const char* mnemonic)
-      : Operator1(opcode, properties, inputs, outputs, mnemonic, controls) {}
+      : Operator1(static_cast<uint8_t>(opcode), properties, inputs, outputs,
+                  mnemonic, controls) {}
 
   virtual OStream& PrintParameter(OStream& os) const { return os; }  // NOLINT
   int ControlInputCount() const { return parameter(); }
@@ -33,9 +34,9 @@ class ControlOperator : public Operator1<int> {
 class CallOperator : public Operator1<CallDescriptor*> {
  public:
   CallOperator(CallDescriptor* descriptor, const char* mnemonic)
-      : Operator1(IrOpcode::kCall, descriptor->properties(),
-                  descriptor->InputCount(), descriptor->ReturnCount(), mnemonic,
-                  descriptor) {}
+      : Operator1(static_cast<uint8_t>(IrOpcode::kCall),
+                  descriptor->properties(), descriptor->InputCount(),
+                  descriptor->ReturnCount(), mnemonic, descriptor) {}
 
   virtual OStream& PrintParameter(OStream& os) const {  // NOLINT
     return os << "[" << *parameter() << "]";