[numeric separator] Add tests for ToNumber

Bug: v8:7317
Change-Id: I2182edc5169c622280a104036ff07507acc01fb9
Reviewed-on: https://chromium-review.googlesource.com/965982Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51988}

test/mjsunit/harmony/numeric-separator.js

@@ -45,6 +45,23 @@
   assertEquals(leadingZeros, 0913);
 }
 
+{
+  const basic = Number('1_2_3');
+  assertEquals(NaN, basic);
+  const exponent = Number('1_0e+1');
+  assertEquals(NaN, exponent);
+  const exponent2 = Number('1_0e+1_0');
+  assertEquals(NaN, exponent2);
+  const hex = Number('0xF_F_FF');
+  assertEquals(NaN, hex);
+  const octal = Number('0o7_7_7');
+  assertEquals(NaN, octal);
+  const binary = Number('0b0_1_0_1_0');
+  assertEquals(NaN, binary);
+  const leadingZeros = Number('09_1_3');
+  assertEquals(NaN, leadingZeros);
+}
+
 assertThrows('1_0_0_0_', SyntaxError);
 assertThrows('1e_1', SyntaxError);
 assertThrows('1e+_1', SyntaxError);