Drop a couple of redundant methods

spec.emu

@@ -705,35 +705,6 @@ location: https://github.com/tc39/proposal-decimal/
     </emu-note>
   </emu-clause>
 
-  <emu-clause id="sec-decimal.prototype.tobigint">
-    <h1>Decimal128.prototype.toBigInt ( )</h1>
-    <p>This method performs the following steps when called:</p>
-    <emu-alg>
-      1. Let _O_ be the *this* value.
-      1. Perform ? RequireInternalSlot(_O_, [[Decimal128Data]]).
-      1. If IsIntegralDecimal128(_O_) is *false*, throw a *RangeError* exception.
-      1. Return ! ToBigInt(Call (_O_.[[toString]], *this*)).
-    </emu-alg>
-    <emu-note>
-      <p>This operation follows the specification of the <code>convertToIntegerTiesToEven</code> operation defined in Section 5.4.1 of <emu-xref href="#sec-bibliography">IEEE 754-2019</emu-xref>.</p>
-    </emu-note>
-  </emu-clause>
-
-  <emu-clause id="sec-decimal.prototype.tonumber">
-    <h1>Decimal128.prototype.toNumber ( )</h1>
-    <p>This method performs the following steps when called:</p>
-    <emu-alg>
-      1. Let _O_ be the *this* value.
-      1. Perform ? RequireInternalSlot(_O_, [[Decimal128Data]]).
-      1. Let _d_ be _O_.[[Decimal128Data]].
-      1. Let _s_ be Decimal128ToDecimalString(_d_).
-      1. Return StringToNumber(_s_).
-    </emu-alg>
-    <emu-note>
-      <p>This operation follows the specification of the conversion operation defined in Section 5.4.2 of <emu-xref href="#sec-bibliography">IEEE 754-2019</emu-xref>.</p>
-    </emu-note>
-  </emu-clause>
-
   <emu-clause id="sec-decimal.prototype.valueof">
     <h1>Decimal128.prototype.valueOf ( _x_ )</h1>
     <p>This method performs the following steps when called:</p>