Add tests for let declarations/identifier variables

tests/baselines/reference/VariableDeclaration12_es6.js

@@ -0,0 +1,7 @@
+//// [VariableDeclaration12_es6.ts]
+
+let
+x
+
+//// [VariableDeclaration12_es6.js]
+let x;

tests/baselines/reference/VariableDeclaration12_es6.symbols

@@ -0,0 +1,6 @@
+=== tests/cases/conformance/es6/variableDeclarations/VariableDeclaration12_es6.ts ===
+
+let
+x
+>x : Symbol(x, Decl(VariableDeclaration12_es6.ts, 1, 3))
+

tests/baselines/reference/VariableDeclaration12_es6.types

@@ -0,0 +1,6 @@
+=== tests/cases/conformance/es6/variableDeclarations/VariableDeclaration12_es6.ts ===
+
+let
+x
+>x : any
+

tests/baselines/reference/VariableDeclaration13_es6.errors.txt

@@ -0,0 +1,20 @@
+tests/cases/conformance/es6/variableDeclarations/VariableDeclaration13_es6.ts(5,5): error TS1181: Array element destructuring pattern expected.
+tests/cases/conformance/es6/variableDeclarations/VariableDeclaration13_es6.ts(5,6): error TS1005: ',' expected.
+tests/cases/conformance/es6/variableDeclarations/VariableDeclaration13_es6.ts(5,8): error TS1134: Variable declaration expected.
+tests/cases/conformance/es6/variableDeclarations/VariableDeclaration13_es6.ts(5,10): error TS1134: Variable declaration expected.
+
+
+==== tests/cases/conformance/es6/variableDeclarations/VariableDeclaration13_es6.ts (4 errors) ====
+
+    // An ExpressionStatement cannot start with the two token sequence `let [` because
+    // that would make it ambiguous with a `let` LexicalDeclaration whose first LexicalBinding was an ArrayBindingPattern.
+    var let: any;
+    let[0] = 100;
+        ~
+!!! error TS1181: Array element destructuring pattern expected.
+         ~
+!!! error TS1005: ',' expected.
+           ~
+!!! error TS1134: Variable declaration expected.
+             ~~~
+!!! error TS1134: Variable declaration expected.

tests/baselines/reference/VariableDeclaration13_es6.js

@@ -0,0 +1,13 @@
+//// [VariableDeclaration13_es6.ts]
+
+// An ExpressionStatement cannot start with the two token sequence `let [` because
+// that would make it ambiguous with a `let` LexicalDeclaration whose first LexicalBinding was an ArrayBindingPattern.
+var let: any;
+let[0] = 100;
+
+//// [VariableDeclaration13_es6.js]
+// An ExpressionStatement cannot start with the two token sequence `let [` because
+// that would make it ambiguous with a `let` LexicalDeclaration whose first LexicalBinding was an ArrayBindingPattern.
+var let;
+let [] = 0;
+100;

tests/baselines/reference/letIdentifierInElementAccess01.js

@@ -0,0 +1,7 @@
+//// [letIdentifierInElementAccess01.ts]
+var let: any = {};
+(let[0] = 100);
+
+//// [letIdentifierInElementAccess01.js]
+var let = {};
+(let[0] = 100);

tests/baselines/reference/letIdentifierInElementAccess01.symbols

@@ -0,0 +1,7 @@
+=== tests/cases/conformance/expressions/elementAccess/letIdentifierInElementAccess01.ts ===
+var let: any = {};
+>let : Symbol(let, Decl(letIdentifierInElementAccess01.ts, 0, 3))
+
+(let[0] = 100);
+>let : Symbol(let, Decl(letIdentifierInElementAccess01.ts, 0, 3))
+

tests/baselines/reference/letIdentifierInElementAccess01.types

@@ -0,0 +1,13 @@
+=== tests/cases/conformance/expressions/elementAccess/letIdentifierInElementAccess01.ts ===
+var let: any = {};
+>let : any
+>{} : {}
+
+(let[0] = 100);
+>(let[0] = 100) : number
+>let[0] = 100 : number
+>let[0] : any
+>let : any
+>0 : number
+>100 : number
+

tests/cases/conformance/es6/variableDeclarations/VariableDeclaration12_es6.ts

@@ -0,0 +1,4 @@
+// @target:es6
+
+let
+x

tests/cases/conformance/es6/variableDeclarations/VariableDeclaration13_es6.ts

@@ -0,0 +1,6 @@
+// @target:es6
+
+// An ExpressionStatement cannot start with the two token sequence `let [` because
+// that would make it ambiguous with a `let` LexicalDeclaration whose first LexicalBinding was an ArrayBindingPattern.
+var let: any;
+let[0] = 100;

tests/cases/conformance/expressions/elementAccess/letIdentifierInElementAccess01.ts

@@ -0,0 +1,2 @@
+var let: any = {};
+(let[0] = 100);