[runtime] [proxy] implement [[Construct]]

src/mips/builtins-mips.cc

Index: src/mips/builtins-mips.cc
diff --git a/src/mips/builtins-mips.cc b/src/mips/builtins-mips.cc
index 9d1473d938c7b7b2ed573baa6a45eac2109d0b50..74720d7beadb937f066b7165d0c6e4fb79c15a74 100644
--- a/src/mips/builtins-mips.cc
+++ b/src/mips/builtins-mips.cc
@@ -1761,8 +1761,14 @@ void Builtins::Generate_ConstructProxy(MacroAssembler* masm) {
   //          the JSFunction on which new was invoked initially)
   // -----------------------------------
 
-  // TODO(neis): This doesn't match the ES6 spec for [[Construct]] on proxies.
-  __ Jump(masm->isolate()->builtins()->Call(), RelocInfo::CODE_TARGET);
+  // Call into the Runtime for Proxy [[Construct]].
+  __ Push(a1);
+  __ Push(a3);
+  // Include the pushed new_target, constructor and the receiver.
+  __ Addu(a0, a0, 3);
+  // Tail-call to the runtime.
+  __ JumpToExternalReference(
+      ExternalReference(Runtime::kJSProxyConstruct, masm->isolate()));
 }
 
 
@@ -1784,14 +1790,16 @@ void Builtins::Generate_Construct(MacroAssembler* masm) {
   __ lbu(t2, FieldMemOperand(t1, Map::kInstanceTypeOffset));
   __ Jump(masm->isolate()->builtins()->ConstructFunction(),
           RelocInfo::CODE_TARGET, eq, t2, Operand(JS_FUNCTION_TYPE));
-  __ Jump(masm->isolate()->builtins()->ConstructProxy(), RelocInfo::CODE_TARGET,
-          eq, t2, Operand(JS_PROXY_TYPE));
 
   // Check if target has a [[Construct]] internal method.
   __ lbu(t2, FieldMemOperand(t1, Map::kBitFieldOffset));
   __ And(t2, t2, Operand(1 << Map::kIsCallable));
   __ Branch(&non_constructor, eq, t2, Operand(zero_reg));
 
+  // Only dispatch to proxies after checking whether they are constructors.
+  __ Jump(masm->isolate()->builtins()->ConstructProxy(), RelocInfo::CODE_TARGET,
+          eq, t2, Operand(JS_PROXY_TYPE));
+
   // Called Construct on an exotic Object with a [[Construct]] internal method.
   {
     // Overwrite the original receiver with the (original) target.