[ESLint] Fix violations when enabling curly rule in eslint.

tracing/tracing/base/math/bbox2.html

Index: tracing/tracing/base/math/bbox2.html
diff --git a/tracing/tracing/base/math/bbox2.html b/tracing/tracing/base/math/bbox2.html
index b7520cb54bb53391e4940c396f8b590af7e1289d..b184414374c1c9ae27cc4a43e81852d1683aa389 100644
--- a/tracing/tracing/base/math/bbox2.html
+++ b/tracing/tracing/base/math/bbox2.html
@@ -39,8 +39,7 @@ tr.exportTo('tr.b.math', function() {
     },
 
     addBBox2: function(bbox2) {
-      if (bbox2.isEmpty)
-        return;
+      if (bbox2.isEmpty) return;
       this.addVec2(bbox2.min_);
       this.addVec2(bbox2.max_);
     },
@@ -95,47 +94,48 @@ tr.exportTo('tr.b.math', function() {
     },
 
     get minVec2() {
-      if (this.isEmpty_)
-        return undefined;
+      if (this.isEmpty_) return undefined;
       return this.min_;
     },
 
     get maxVec2() {
-      if (this.isEmpty_)
-        return undefined;
+      if (this.isEmpty_) return undefined;
       return this.max_;
     },
 
     get sizeAsVec2() {
-      if (this.isEmpty_)
+      if (this.isEmpty_) {
         throw new Error('Empty BBox2 has no size');
+      }
       var size = vec2.create();
       vec2.subtract(size, this.max_, this.min_);
       return size;
     },
 
     get size() {
-      if (this.isEmpty_)
+      if (this.isEmpty_) {
         throw new Error('Empty BBox2 has no size');
+      }
       return {width: this.max_[0] - this.min_[0],
         height: this.max_[1] - this.min_[1]};
     },
 
     get width() {
-      if (this.isEmpty_)
+      if (this.isEmpty_) {
         throw new Error('Empty BBox2 has no width');
+      }
       return this.max_[0] - this.min_[0];
     },
 
     get height() {
-      if (this.isEmpty_)
+      if (this.isEmpty_) {
         throw new Error('Empty BBox2 has no width');
+      }
       return this.max_[1] - this.min_[1];
     },
 
     toString: function() {
-      if (this.isEmpty_)
-        return 'empty';
+      if (this.isEmpty_) return 'empty';
       return 'min=(' + this.min_[0] + ',' + this.min_[1] + ') ' +
           'max=(' + this.max_[0] + ',' + this.max_[1] + ')';
     },