Remove TODOs that won't be addressed

packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol

@@ -374,21 +374,19 @@ contract MixinExchangeCore is
         returns (FillResults memory fillResults)
     {
         // Compute proportional transfer amounts
-        // TODO: All three are multiplied by the same fraction. This can
-        // potentially be optimized.
         fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
         fillResults.makerAssetFilledAmount = getPartialAmount(
-            fillResults.takerAssetFilledAmount,
+            takerAssetFilledAmount,
             order.takerAssetAmount,
             order.makerAssetAmount
         );
         fillResults.makerFeePaid = getPartialAmount(
-            fillResults.takerAssetFilledAmount,
+            takerAssetFilledAmount,
             order.takerAssetAmount,
             order.makerFee
         );
         fillResults.takerFeePaid = getPartialAmount(
-            fillResults.takerAssetFilledAmount,
+            takerAssetFilledAmount,
             order.takerAssetAmount,
             order.takerFee
         );

packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol

@@ -41,7 +41,6 @@ contract MixinMatchOrders is
     /// @param leftSignature Proof that order was created by the left maker.
     /// @param rightSignature Proof that order was created by the right maker.
     /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
-    /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
     function matchOrders(
         LibOrder.Order memory leftOrder,
         LibOrder.Order memory rightOrder,
@@ -184,7 +183,6 @@ contract MixinMatchOrders is
             leftTakerAssetFilledAmount = leftTakerAssetAmountRemaining;
 
             // The right order receives an amount proportional to how much was spent.
-            // TODO: Can we ensure rounding error is in the correct direction?
             rightTakerAssetFilledAmount = getPartialAmount(
                 rightOrder.takerAssetAmount,
                 rightOrder.makerAssetAmount,
@@ -195,7 +193,6 @@ contract MixinMatchOrders is
             rightTakerAssetFilledAmount = rightTakerAssetAmountRemaining;
 
             // The left order receives an amount proportional to how much was spent.
-            // TODO: Can we ensure rounding error is in the correct direction?
             leftTakerAssetFilledAmount = getPartialAmount(
                 rightOrder.makerAssetAmount,
                 rightOrder.takerAssetAmount,

packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol

@@ -91,7 +91,6 @@ contract MixinSignatureValidator is
         view
         returns (bool isValid)
     {
-        // TODO: Domain separation: make hash depend on role. (Taker sig should not be valid as maker sig, etc.)
         require(
             signature.length > 0,
             "LENGTH_GREATER_THAN_0_REQUIRED"

packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol

@@ -33,7 +33,6 @@ contract IMatchOrders {
     /// @param leftSignature Proof that order was created by the left maker.
     /// @param rightSignature Proof that order was created by the right maker.
     /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
-    /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
     function matchOrders(
         LibOrder.Order memory leftOrder,
         LibOrder.Order memory rightOrder,