Syncing naming of value and amount. (#1895)

(cherry picked from commit 5d183d0e)

contracts/token/ERC20/ERC20.sol

@@ -78,8 +78,8 @@ contract ERC20 is Context, IERC20 {
      *
      * - `spender` cannot be the zero address.
      */
-    function approve(address spender, uint256 value) public returns (bool) {
-        _approve(_msgSender(), spender, value);
+    function approve(address spender, uint256 amount) public returns (bool) {
+        _approve(_msgSender(), spender, amount);
         return true;
     }
 
@@ -91,7 +91,7 @@ contract ERC20 is Context, IERC20 {
      *
      * Requirements:
      * - `sender` and `recipient` cannot be the zero address.
-     * - `sender` must have a balance of at least `value`.
+     * - `sender` must have a balance of at least `amount`.
      * - the caller must have allowance for `sender`'s tokens of at least
      * `amount`.
      */
@@ -188,12 +188,12 @@ contract ERC20 is Context, IERC20 {
      * - `account` cannot be the zero address.
      * - `account` must have at least `amount` tokens.
      */
-    function _burn(address account, uint256 value) internal {
+    function _burn(address account, uint256 amount) internal {
         require(account != address(0), "ERC20: burn from the zero address");
 
-        _balances[account] = _balances[account].sub(value, "ERC20: burn amount exceeds balance");
-        _totalSupply = _totalSupply.sub(value);
-        emit Transfer(account, address(0), value);
+        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
+        _totalSupply = _totalSupply.sub(amount);
+        emit Transfer(account, address(0), amount);
     }
 
     /**
@@ -209,12 +209,12 @@ contract ERC20 is Context, IERC20 {
      * - `owner` cannot be the zero address.
      * - `spender` cannot be the zero address.
      */
-    function _approve(address owner, address spender, uint256 value) internal {
+    function _approve(address owner, address spender, uint256 amount) internal {
         require(owner != address(0), "ERC20: approve from the zero address");
         require(spender != address(0), "ERC20: approve to the zero address");
 
-        _allowances[owner][spender] = value;
-        emit Approval(owner, spender, value);
+        _allowances[owner][spender] = amount;
+        emit Approval(owner, spender, amount);
     }
 
     /**