Addressed CR feedback, also properly accounted for template literals.

Author: DanielRosenwasser

src/compiler/emitter.ts

@@ -2193,13 +2193,7 @@ module ts {
             }
 
             function emitLiteral(node: LiteralExpression) {
-                var text = languageVersion < ScriptTarget.ES6 && (isTemplateLiteralKind(node.kind) || node.hasExtendedUnicodeEscape)
-                    ? getDoubleQuotedStringTextOfLiteral(node)
-                    : node.parent
-                        ? getSourceTextOfNodeFromSourceFile(currentSourceFile, node)
-                        : node.kind === SyntaxKind.NumericLiteral
-                            ? node.text
-                            : getDoubleQuotedStringTextOfLiteral(node);
+                var text = getLiteralText(node);
 
                 if (compilerOptions.sourceMap && (node.kind === SyntaxKind.StringLiteral || isTemplateLiteralKind(node.kind))) {
                     writer.writeLiteral(text);
@@ -2213,11 +2207,41 @@ module ts {
                 }
             }
 
-            function getDoubleQuotedStringTextOfLiteral(node: LiteralExpression): string {
-                var result = escapeString(node.text);
-                result = escapeNonAsciiCharacters(result);
+            function getLiteralText(node: LiteralExpression) {
+                // Any template literal or string literal with an extended escape
+                // (e.g. "\u{0067}") will need to be downleveled as a escaped string literal.
+                if (languageVersion < ScriptTarget.ES6 && (isTemplateLiteralKind(node.kind) || node.hasExtendedUnicodeEscape)) {
+                    return getQuotedEscapedLiteralText('"', node.text, '"');
+                }
+                
+                // If we don't need to downlevel, and we can reach the original source text using
+                // the node's parent reference, then simply get the text as it was originally written.
+                if (node.parent) {
+                    return getSourceTextOfNodeFromSourceFile(currentSourceFile, node);
+                }
 
-                return '"' + result + '"';
+                // If we can't reach the original source text, use the canonical form of it's a number,
+                // or a escaped quoted form of the original text if it's string-like.
+                switch (node.kind) {
+                    case SyntaxKind.StringLiteral:
+                        return getQuotedEscapedLiteralText('"', node.text, '"');
+                    case SyntaxKind.NoSubstitutionTemplateLiteral:
+                        return getQuotedEscapedLiteralText('`', node.text, '`');
+                    case SyntaxKind.TemplateHead:
+                        return getQuotedEscapedLiteralText('`', node.text, '${');
+                    case SyntaxKind.TemplateMiddle:
+                        return getQuotedEscapedLiteralText('}', node.text, '${');
+                    case SyntaxKind.TemplateTail:
+                        return getQuotedEscapedLiteralText('}', node.text, '`');
+                    case SyntaxKind.NumericLiteral:
+                        return node.text;
+                }
+                
+                Debug.fail(`Literal kind '${node.kind}' not accounted for.`);
+            }
+            
+            function getQuotedEscapedLiteralText(leftQuote: string, text: string, rightQuote: string) {
+                return leftQuote + escapeNonAsciiCharacters(escapeString(text)) + rightQuote;
             }
 
             function emitDownlevelRawTemplateLiteral(node: LiteralExpression) {

src/compiler/utilities.ts

@@ -1130,7 +1130,7 @@ module ts {
             newEndN = Math.max(newEnd2, newEnd2 + (newEnd1 - oldEnd2));
         }
 
-        return createTextChangeRange(createTextSpanFromBounds(oldStartN, oldEndN), /*newLength*/ newEndN - oldStartN);
+        return createTextChangeRange(createTextSpanFromBounds(oldStartN, oldEndN), /*newLength:*/ newEndN - oldStartN);
     }
 
     // @internal