--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -2059,18 +2059,16 @@ EmitNameOp(ExclusiveContext *cx, Bytecod
     if (callContext) {
         if (op == JSOP_CALLNAME && bce->needsImplicitThis()) {
             if (!EmitAtomOp(cx, pn, JSOP_IMPLICITTHIS, bce))
                 return false;
         } else {
             if (Emit1(cx, bce, JSOP_UNDEFINED) < 0)
                 return false;
         }
-        if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-            return false;
     }
 
     return true;
 }
 
 static bool
 EmitPropLHS(ExclusiveContext *cx, ParseNode *pn, JSOp op, BytecodeEmitter *bce)
 {
@@ -2131,19 +2129,16 @@ EmitPropOp(ExclusiveContext *cx, ParseNo
         return false;
 
     if (!EmitAtomOp(cx, pn, op, bce))
         return false;
 
     if (op == JSOP_CALLPROP && Emit1(cx, bce, JSOP_SWAP) < 0)
         return false;
 
-    if (op == JSOP_CALLPROP && Emit1(cx, bce, JSOP_NOTEARG) < 0)
-        return false;
-
     return true;
 }
 
 static bool
 EmitPropIncDec(ExclusiveContext *cx, ParseNode *pn, BytecodeEmitter *bce)
 {
     JS_ASSERT(pn->pn_kid->getKind() == PNK_DOT);
 
@@ -2243,18 +2238,16 @@ EmitElemOpBase(ExclusiveContext *cx, Byt
 {
     if (Emit1(cx, bce, op) < 0)
         return false;
     CheckTypeSet(cx, bce, op);
 
     if (op == JSOP_CALLELEM) {
         if (Emit1(cx, bce, JSOP_SWAP) < 0)
             return false;
-        if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-            return false;
     }
     return true;
 }
 
 static bool
 EmitElemOp(ExclusiveContext *cx, ParseNode *pn, JSOp op, BytecodeEmitter *bce)
 {
     return EmitElemOperands(cx, pn, op, bce) && EmitElemOpBase(cx, bce, op);
@@ -4352,18 +4345,16 @@ EmitForOf(ExclusiveContext *cx, Bytecode
 
     // Convert iterable to iterator.
     if (Emit1(cx, bce, JSOP_DUP) < 0)                          // OBJ OBJ
         return false;
     if (!EmitAtomOp(cx, cx->names().std_iterator, JSOP_CALLPROP, bce)) // OBJ @@ITERATOR
         return false;
     if (Emit1(cx, bce, JSOP_SWAP) < 0)                         // @@ITERATOR OBJ
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-        return false;
     if (EmitCall(cx, bce, JSOP_CALL, 0) < 0)                   // ITER
         return false;
     CheckTypeSet(cx, bce, JSOP_CALL);
 
     // Push a dummy result so that we properly enter iteration midstream.
     if (Emit1(cx, bce, JSOP_UNDEFINED) < 0)                    // ITER RESULT
         return false;
 
@@ -4429,22 +4420,18 @@ EmitForOf(ExclusiveContext *cx, Bytecode
     if (Emit1(cx, bce, JSOP_DUP) < 0)                          // ITER ITER
         return false;
     if (Emit1(cx, bce, JSOP_DUP) < 0)                          // ITER ITER ITER
         return false;
     if (!EmitAtomOp(cx, cx->names().next, JSOP_CALLPROP, bce)) // ITER ITER NEXT
         return false;
     if (Emit1(cx, bce, JSOP_SWAP) < 0)                         // ITER NEXT ITER
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-        return false;
     if (Emit1(cx, bce, JSOP_UNDEFINED) < 0)                    // ITER NEXT ITER UNDEFINED
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-        return false;
     if (EmitCall(cx, bce, JSOP_CALL, 1) < 0)                   // ITER RESULT
         return false;
     CheckTypeSet(cx, bce, JSOP_CALL);
     if (Emit1(cx, bce, JSOP_DUP) < 0)                          // ITER RESULT RESULT
         return false;
     if (!EmitAtomOp(cx, cx->names().done, JSOP_GETPROP, bce))  // ITER RESULT DONE?
         return false;
 
@@ -5159,18 +5146,16 @@ EmitYieldStar(ExclusiveContext *cx, Byte
 
     // Convert iterable to iterator.
     if (Emit1(cx, bce, JSOP_DUP) < 0)                            // ITERABLE ITERABLE
         return false;
     if (!EmitAtomOp(cx, cx->names().std_iterator, JSOP_CALLPROP, bce)) // ITERABLE @@ITERATOR
         return false;
     if (Emit1(cx, bce, JSOP_SWAP) < 0)                           // @@ITERATOR ITERABLE
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-        return false;
     if (EmitCall(cx, bce, JSOP_CALL, 0) < 0)                     // ITER
         return false;
     CheckTypeSet(cx, bce, JSOP_CALL);
 
     int depth = bce->stackDepth;
     JS_ASSERT(depth >= 1);
 
     // Initial send value is undefined.
@@ -5231,22 +5216,18 @@ EmitYieldStar(ExclusiveContext *cx, Byte
     if (Emit1(cx, bce, JSOP_DUP) < 0)                            // EXCEPTION ITER ITER
         return false;
     if (Emit1(cx, bce, JSOP_DUP) < 0)                            // EXCEPTION ITER ITER ITER
         return false;
     if (!EmitAtomOp(cx, cx->names().throw_, JSOP_CALLPROP, bce)) // EXCEPTION ITER ITER THROW
         return false;
     if (Emit1(cx, bce, JSOP_SWAP) < 0)                           // EXCEPTION ITER THROW ITER
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)                        // EXCEPTION ITER THROW ITER
-        return false;
     if (Emit2(cx, bce, JSOP_PICK, (jsbytecode)3) < 0)            // ITER THROW ITER EXCEPTION
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)                        // ITER THROW ITER EXCEPTION
-        return false;
     if (EmitCall(cx, bce, JSOP_CALL, 1) < 0)                     // ITER RESULT
         return false;
     CheckTypeSet(cx, bce, JSOP_CALL);
     JS_ASSERT(bce->stackDepth == depth + 1);
     ptrdiff_t checkResult = -1;
     if (EmitBackPatchOp(cx, bce, &checkResult) < 0)              // goto checkResult
         return false;
 
@@ -5272,22 +5253,18 @@ EmitYieldStar(ExclusiveContext *cx, Byte
     if (Emit1(cx, bce, JSOP_DUP) < 0)                            // RECEIVED ITER ITER
         return false;
     if (Emit1(cx, bce, JSOP_DUP) < 0)                            // RECEIVED ITER ITER ITER
         return false;
     if (!EmitAtomOp(cx, cx->names().next, JSOP_CALLPROP, bce))   // RECEIVED ITER ITER NEXT
         return false;
     if (Emit1(cx, bce, JSOP_SWAP) < 0)                           // RECEIVED ITER NEXT ITER
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)                        // RECEIVED ITER NEXT ITER
-        return false;
     if (Emit2(cx, bce, JSOP_PICK, (jsbytecode)3) < 0)            // ITER NEXT ITER RECEIVED
         return false;
-    if (Emit1(cx, bce, JSOP_NOTEARG) < 0)                        // ITER NEXT ITER RECEIVED
-        return false;
     if (EmitCall(cx, bce, JSOP_CALL, 1) < 0)                     // ITER RESULT
         return false;
     CheckTypeSet(cx, bce, JSOP_CALL);
     JS_ASSERT(bce->stackDepth == depth + 1);
 
     if (!BackPatch(cx, bce, checkResult, bce->code().end(), JSOP_GOTO)) // checkResult:
         return false;
     // if (!result.done) goto tryStart;                          // ITER RESULT
@@ -5523,25 +5500,21 @@ EmitCallOrNew(ExclusiveContext *cx, Byte
                 return false;
             }
             ParseNode *funNode = pn2->pn_next;
             if (!EmitTree(cx, bce, funNode))
                 return false;
             ParseNode *thisArg = funNode->pn_next;
             if (!EmitTree(cx, bce, thisArg))
                 return false;
-            if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-                return false;
             bool oldEmittingForInit = bce->emittingForInit;
             bce->emittingForInit = false;
             for (ParseNode *argpn = thisArg->pn_next; argpn; argpn = argpn->pn_next) {
                 if (!EmitTree(cx, bce, argpn))
                     return false;
-                if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-                    return false;
             }
             bce->emittingForInit = oldEmittingForInit;
             argc -= 2;
             emitArgs = false;
             break;
         }
         if (!EmitNameOp(cx, bce, pn2, callop))
             return false;
@@ -5582,34 +5555,30 @@ EmitCallOrNew(ExclusiveContext *cx, Byte
             return false;
         callop = false;             /* trigger JSOP_UNDEFINED after */
         break;
     }
     if (!callop) {
         JSOp thisop = pn->isKind(PNK_GENEXP) ? JSOP_THIS : JSOP_UNDEFINED;
         if (Emit1(cx, bce, thisop) < 0)
             return false;
-        if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-            return false;
     }
 
     if (emitArgs) {
         /*
          * Emit code for each argument in order, then emit the JSOP_*CALL or
          * JSOP_NEW bytecode with a two-byte immediate telling how many args
          * were pushed on the operand stack.
          */
         bool oldEmittingForInit = bce->emittingForInit;
         bce->emittingForInit = false;
         if (!spread) {
             for (ParseNode *pn3 = pn2->pn_next; pn3; pn3 = pn3->pn_next) {
                 if (!EmitTree(cx, bce, pn3))
                     return false;
-                if (Emit1(cx, bce, JSOP_NOTEARG) < 0)
-                    return false;
             }
         } else {
             if (!EmitArray(cx, bce, pn2->pn_next, argc))
                 return false;
         }
         bce->emittingForInit = oldEmittingForInit;
     }
 

--- a/js/src/jit/BaselineCompiler.cpp
+++ b/js/src/jit/BaselineCompiler.cpp
@@ -835,22 +835,16 @@ BaselineCompiler::emit_JSOP_NOP()
 
 bool
 BaselineCompiler::emit_JSOP_LABEL()
 {
     return true;
 }
 
 bool
-BaselineCompiler::emit_JSOP_NOTEARG()
-{
-    return true;
-}
-
-bool
 BaselineCompiler::emit_JSOP_POP()
 {
     frame.pop();
     return true;
 }
 
 bool
 BaselineCompiler::emit_JSOP_POPN()

--- a/js/src/jit/BaselineCompiler.h
+++ b/js/src/jit/BaselineCompiler.h
@@ -19,17 +19,16 @@
 #endif
 
 namespace js {
 namespace jit {
 
 #define OPCODE_LIST(_)         \
     _(JSOP_NOP)                \
     _(JSOP_LABEL)              \
-    _(JSOP_NOTEARG)            \
     _(JSOP_POP)                \
     _(JSOP_POPN)               \
     _(JSOP_POPNV)              \
     _(JSOP_DUP)                \
     _(JSOP_DUP2)               \
     _(JSOP_SWAP)               \
     _(JSOP_PICK)               \
     _(JSOP_GOTO)               \

--- a/js/src/jit/IonBuilder.cpp
+++ b/js/src/jit/IonBuilder.cpp
@@ -1507,19 +1507,16 @@ IonBuilder::inspectOpcode(JSOp op)
         return jsop_arguments();
 
       case JSOP_RUNONCE:
         return jsop_runonce();
 
       case JSOP_REST:
         return jsop_rest();
 
-      case JSOP_NOTEARG:
-        return jsop_notearg();
-
       case JSOP_GETARG:
       case JSOP_CALLARG:
         if (info().argsObjAliasesFormals()) {
             MGetArgumentsObjectArg *getArg = MGetArgumentsObjectArg::New(alloc(),
                                                                          current->argumentsObject(),
                                                                          GET_SLOTNO(pc));
             current->add(getArg);
             current->push(getArg);
@@ -3808,23 +3805,16 @@ IonBuilder::jsop_neg()
 
     MDefinition *right = current->pop();
 
     if (!jsop_binary(JSOP_MUL, negator, right))
         return false;
     return true;
 }
 
-bool
-IonBuilder::jsop_notearg()
-{
-    // :TODO: Remove JSOP_NOTEARG (bug 953284).
-    return true;
-}
-
 class AutoAccumulateReturns
 {
     MIRGraph &graph_;
     MIRGraphReturns *prev_;
 
   public:
     AutoAccumulateReturns(MIRGraph &graph, MIRGraphReturns &returns)
       : graph_(graph)

--- a/js/src/jsopcode.tbl
+++ b/js/src/jsopcode.tbl
@@ -488,24 +488,22 @@ OPDEF(JSOP_IMPLICITTHIS,  226, "implicit
 
 /*
  * This opcode is the target of the entry jump for some loop. The uint8 argument
  * is the loop depth. This value starts at 1 and is just a hint: deeply
  * nested loops all have the same value.
  */
 OPDEF(JSOP_LOOPENTRY,     227, "loopentry",    NULL,  2,  0,  0,  JOF_UINT8)
 
-/* Notes the point at which a value is pushed as an argument. */
-OPDEF(JSOP_NOTEARG,       228, "notearg",      NULL,  1,  0,  0,  JOF_BYTE)
-
 /*
  * Pad out the unused opcode space to the nearest power-of-two boundary. The
  * interpreter uses this to construct a table which is a power-of-two size.
  */
 #ifdef OPPAD
+OPPAD(228)
 OPPAD(229)
 OPPAD(230)
 OPPAD(231)
 OPPAD(232)
 OPPAD(233)
 OPPAD(234)
 OPPAD(235)
 OPPAD(236)

--- a/js/src/vm/Interpreter.cpp
+++ b/js/src/vm/Interpreter.cpp
@@ -1705,19 +1705,16 @@ CASE(JSOP_LOOPENTRY)
                 goto jit_return_pop_frame;
             goto leave_on_safe_point;
         }
     }
 #endif /* JS_ION */
 
 END_CASE(JSOP_LOOPENTRY)
 
-CASE(JSOP_NOTEARG)
-END_CASE(JSOP_NOTEARG)
-
 CASE(JSOP_LINENO)
 END_CASE(JSOP_LINENO)
 
 CASE(JSOP_UNDEFINED)
     PUSH_UNDEFINED();
 END_CASE(JSOP_UNDEFINED)
 
 CASE(JSOP_POP)

--- a/js/src/vm/Xdr.h
+++ b/js/src/vm/Xdr.h
@@ -17,17 +17,17 @@ namespace js {
  * Bytecode version number. Increment the subtrahend whenever JS bytecode
  * changes incompatibly.
  *
  * This version number is XDR'd near the front of xdr bytecode and
  * aborts deserialization if there is a mismatch between the current
  * and saved versions. If deserialization fails, the data should be
  * invalidated if possible.
  */
-static const uint32_t XDR_BYTECODE_VERSION = uint32_t(0xb973c0de - 159);
+static const uint32_t XDR_BYTECODE_VERSION = uint32_t(0xb973c0de - 160);
 
 class XDRBuffer {
   public:
     XDRBuffer(JSContext *cx)
       : context(cx), base(nullptr), cursor(nullptr), limit(nullptr) { }
 
     JSContext *cx() const {
         return context;