[parser] Lift template literal invalid escape restriction

src/parsing/scanner.cc

Index: src/parsing/scanner.cc
diff --git a/src/parsing/scanner.cc b/src/parsing/scanner.cc
index bfb5e03d68457841d0bb4e72b5632e7b97a77324..346ca676835d6c1f15c66dac16c1098bfe79fcf3 100644
--- a/src/parsing/scanner.cc
+++ b/src/parsing/scanner.cc
@@ -948,16 +948,12 @@ bool Scanner::ScanEscape() {
       break;
   }
 
-  // According to ECMA-262, section 7.8.4, characters not covered by the
-  // above cases should be illegal, but they are commonly handled as
-  // non-escaped characters by JS VMs.
+  // Other escaped characters are interpreted as their non-escaped version.
   AddLiteralChar(c);
   return true;
 }
 
 
-// Octal escapes of the forms '\0xx' and '\xxx' are not a part of
-// ECMA-262. Other JS VMs support them.
 template <bool capture_raw>
 uc32 Scanner::ScanOctalEscape(uc32 c, int length) {
   uc32 x = c - '0';
@@ -1069,8 +1065,10 @@ Token::Value Scanner::ScanTemplateSpan() {
             AddRawLiteralChar('\n');
           }
         }
-      } else if (!ScanEscape<capture_raw, in_template_literal>()) {
-        return Token::ILLEGAL;
+      } else {
+        // For templates, invalid escape sequence checking is handled in the
+        // parser.
+        ScanEscape<capture_raw, in_template_literal>();
       }
     } else if (c < 0) {
       // Unterminated template literal