Removed unnecessary case; substitution expressions only occur in TemplateSpans.

Author: DanielRosenwasser

src/compiler/checker.ts

@@ -4978,8 +4978,6 @@ module ts {
                     return getContextualTypeForElementExpression(node);
                 case SyntaxKind.ConditionalExpression:
                     return getContextualTypeForConditionalOperand(node);
-                case SyntaxKind.TemplateExpression:
-                    return getContextualTypeForSubstitutionExpression(<TemplateExpression>parent.parent, node);
                 case SyntaxKind.TemplateSpan:
                     Debug.assert(parent.parent.kind === SyntaxKind.TemplateExpression);
                     return getContextualTypeForSubstitutionExpression(<TemplateExpression>parent.parent, node);