DevTools: [SASS] introduce sass module, implement SCSS AST-builder.

third_party/WebKit/LayoutTests/inspector/sass/test-ast-scss-2-expected.txt

+Verifies SCSS AST in case of variables.
+
+$my-color: red;
+$my-font: Arial;
+$class-slug: box;
+
+@for $i from 1 through 3 {
+    .#{$class-slug}#{$i} {
+        background-color: $my-color;
+        font-family: $my-font;
+        /* color: $my-color; */
+    }
+}
+
+=== AST === 
+rule 0: "variables"
+    property 0
+        name: "$my-color"
+            range: {"startLine":0,"startColumn":0,"endLine":0,"endColumn":9}
+        value: " red"
+            range: {"startLine":0,"startColumn":10,"endLine":0,"endColumn":14}
+        range: {"startLine":0,"startColumn":0,"endLine":0,"endColumn":15}
+        disabled: false
+    property 1
+        name: "$my-font"
+            range: {"startLine":1,"startColumn":0,"endLine":1,"endColumn":8}
+        value: " Arial"
+            range: {"startLine":1,"startColumn":9,"endLine":1,"endColumn":15}
+        range: {"startLine":1,"startColumn":0,"endLine":1,"endColumn":16}
+        disabled: false
+    property 2
+        name: "$class-slug"
+            range: {"startLine":2,"startColumn":0,"endLine":2,"endColumn":11}
+        value: " box"
+            range: {"startLine":2,"startColumn":12,"endLine":2,"endColumn":16}
+        range: {"startLine":2,"startColumn":0,"endLine":2,"endColumn":17}
+        disabled: false
+rule 1: "properties"
+    property 0
+        name: "background-color"
+            range: {"startLine":6,"startColumn":8,"endLine":6,"endColumn":24}
+        value: " $my-color"
+            range: {"startLine":6,"startColumn":25,"endLine":6,"endColumn":35}
+        range: {"startLine":6,"startColumn":8,"endLine":6,"endColumn":36}
+        disabled: false
+    property 1
+        name: "font-family"
+            range: {"startLine":7,"startColumn":8,"endLine":7,"endColumn":19}
+        value: " $my-font"
+            range: {"startLine":7,"startColumn":20,"endLine":7,"endColumn":29}
+        range: {"startLine":7,"startColumn":8,"endLine":7,"endColumn":30}
+        disabled: false
+    property 2
+        name: "color"
+            range: {"startLine":8,"startColumn":11,"endLine":8,"endColumn":16}
+        value: " $my-color"
+            range: {"startLine":8,"startColumn":17,"endLine":8,"endColumn":27}
+        range: {"startLine":8,"startColumn":8,"endLine":8,"endColumn":31}
+        disabled: true
+rule 2: "mixins"
+======
+Ranges OK.
+